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This study aims to investigate the reduction of drag forces on roadside billboards using ANSYS Fluent (CFX 2022 R2) simulation and the prevention of accidents caused by them. The excessive drag force generated by the wind on the billboards can cause accidents, particularly for motorcyclists and bicyclists, leading to serious injuries and fatalities. Therefore, this study focuses on the optimization of the billboard design to reduce the drag force and enhance the safety of the roads. The numerical method simulation tool is used to model the aerodynamic behavior of the billboard and identify the factors that influence the drag force. Different design modifications are proposed and analyzed to determine their effectiveness in reducing the drag force. In this study, different structural models are analyzed, and drag force is calculated on the same. Additionally, the study also evaluates the impact of the billboard design on the visibility of drivers and the safety of the surrounding environment. The study resulted in an optimum structural model with a drag force of 319803.08 N with an air velocity strike of 50 kmph over the surface of the billboard. The outcome of this study would help billboard designers and manufacturers create safer and more efficient designs, reduce the risk of accidents, and enhance the overall safety of the transportation system. [ABSTRACT FROM AUTHOR]

The primary goal of the proposed article is the numerical analysis of the Wing model with and without raked winglets. In order to highlight the significant performance and parameter variations between the designs, the investigation here analyses the parameters of wings made with and without serrated raked winglets. Here, the lift-to-drag ratio, lift coefficient, and drag coefficient were the main topics of conversation. This study's tapered wing design was based on the NACA 653-218 air foil. The geometry of the models is implemented and developed using the Solid Works programme. The main objectives of this work are to enhance flight performance by reducing the induced drag that is produced on the wings during action using ANSYS Fluent. It is found that the Serrated Raked Winglet (SRW) gives better reduction in drag and turbulence than the existing normal raked winglet without affecting its lift more at higher angle of attack. [ABSTRACT FROM AUTHOR]

Automotive industry is striving for better efficiency from the vehicle whether it is in terms of design or in engine performance. This research paper reports about the similar attempt on better aerodynamic design. A spherical diffuser is designed for passenger automobile for better efficiency and one that does not have to compromise with space. Design complication of vehicle and diffuser is also discussed. The design model has been made on SolidWorks and tested on CFD (Ansys Fluent) at free stream velocity of 40 m/s with moving ground, initially the test was performed on Ahmed body after that on 1/3 Hatchback model. In both the cases drag and lift reduction is achieved. On Ahmed body 29.9% drag and 103.43% lift reduction is achieved. Research's whole motive is to reduce drag and lift without any additional requirement of space on an Automobile body. [ABSTRACT FROM AUTHOR]

Transporting the oil from station to station in pipelines faces a drag in flow pipe, resulting from the friction between the oil and the inner wall of the pipeline, which is resulting in cost increasing with large amount of money in order to pressure recovery again. In this study, a Passive Flow Control (Vortex Generators) has been proposed for drag reduction in pipe flow. Vortex Generators (VGs) has been installed on the inner surface to change the flow turbulence structure. Numerical simulation via ANSYS software was adopted to study the flow behavior inside the pipeline with various number and height of VGs. The working fluid was considered water. The simulation results were validated to the theoretical results to verify the validity of simulation procedure. Drag reduction has been used as a performance indicator of all cases with various VGs height, VGs number and Re. VGs with height 3 mm showed better drag reduction compared to 5VGs and 10VGs. The maximum drag reduction was 8.7% achieved by 15 VGs. It is recommended to an experimental study of the VGs technique and extend numerically cases. [ABSTRACT FROM AUTHOR]

Automobile Engineers have been trying to introduce the application of using dimples to reduce the drag of both road and air vehicles. Developments in automobile industry have led to increased fuel consumption, thereby increasing the need to reduce the fuel consumption. About 60 percentage of the total drag created due to the relative motion between vehicle and air is created at the rear end of the vehicle due to the formation of wake. The major means of drag experienced by a bluff body is the pressure or form drag. Whereas, the main cause of drag for a streamlined body is the skin friction drag which is due to the resistance offered by the friction on the vehicle skin. The present work intends to describe the variations in coefficient of drag of Ahmed body by modifying the top surface of the body using surface dimples of constant diameter 10 mm, constant dimple ratio (ratio of depth of dimple to diameter of dimple) and varying the number of dimples. To accomplish this, the Ahmed body was designed in CATIA@ and the CFD analysis was carried out using ANSYS Fluent@ solver. The drag reduces and also increases for specific patterns of dimples. The results obtained show that the minimum reduction of drag has been obtained for 1 and 5 dimples which is 2.05 percentage and a maximum reduction of drag has been obtained for 3 dimples which is 3.42 percentage. The drag increased gradually if the number of dimples increased beyond 5. The outcomes are validated with different research works in existence and significant conclusions are obtained. [ABSTRACT FROM AUTHOR]

Accurately predicting the motion of resident space objects requires knowledge of all forces acting on these objects. Ionospheric aerodynamic forces, resulting from the interaction of charged bodies with the plasma medium, have been shown to constitute a significant increase in aerodynamic drag in many regimes of low earth orbit (LEO). Previous work on charged aerodynamics has considered only single species plasma flows, neglecting the multi-species interactions in the region of the ionosphere where O+ and H+ mix. We focus on H+ dominated higher altitude regime. The simulations are performed using a hybrid electrostatic particle in cell code (pdFoam). Distinct drag characteristics of H+ and O+ were identified, and related to the sheath structure for each of these regimes. Drag coefficients for high charge density flows with a mix of H+ and O+ were found to behave in a manner similar to a pure H+ flow, with the O+ component behaving similarly to a neutral flow. This results in a reduction in drag contributed by the Oxygen plasma in these mixed flows. Drag forces on these flows were found to be well predicted by the use of the drag prediction model in Capon et al [1] for H+ components, and equivalent neutral oxygen density for oxygen components. [ABSTRACT FROM AUTHOR]

Among active flow control methods, a counter-flow jet is known to be efficient in supersonic to hypersonic flow regimes for drag reduction at high-Reynolds number regime. In order to apply the counter-flow jet in various flight environments, it is necessary to investigate the effect of drag reduction at not only low and medium altitudes but also high ones with low atmospheric density. To investigate the effect of the Reynolds number on drag reduction with the counter-flow jet, the stagnation pressure ratio (PR) defined as the ratio of the stagnation pressure of the counter-flow jet to that of the free-stream flow is fixed to 1.05, at which the flow field is known to be classified as short penetration mode (SPM) in high-Reynolds number regime. The Mach numbers of the free-stream flow and counter-flow jet are 6 and 2.86, respectively. The stagnation pressure of the free-stream flow is varied from 6.9 kPa to 20 kPa and the stagnation temperature of the free-stream flow and counter-flow jet is 610 K and 294 K, respectively. The maximum Knudsen number based on the radius of the hemisphere model is 0.01. The numerical simulations were performed solving the laminar, unsteady, axisymmetric Navier-Stokes equations by the symmetric TVD scheme with the second-order accuracy in space and the explicit strong stability preserving Runge-Kutta (SSPRK) method. The numerical results show that at the same stagnation PR, shock structure, the penetration length to the flow field, and drag reduction effect are almost identical irrespective of the difference in the free-stream stagnation pressure. Moreover, by decreasing the Reynolds number, the flow field becomes more stable due to the viscosity effect. [ABSTRACT FROM AUTHOR]

A hypervelocity vehicle is moving at high speed, it experiences a tremendous drag and surface heat flux. Hence there is a need of thermal protection system to reduce the surface aerodynamic drag and heat flux. A mechanical spike is a simple yet effective active technique that can decrease drag and heating. This study analyzed a 60° blunted body with a mechanical spike attached, using ANSYS Fluent commercial code. The analysis was conducted at a Mach number of 8.0, with an angle of attack of 0 degrees, and aerodisk length to base diameter (L/D) ratios of 0.5, 0.7, and 1.0. Due to the attachment of an aerodisk to the nose region of the blunt body, flow separation occurs, resulting in the development of a dead air region ahead of the body, which reduces drag and heating. Increasing the length of the aerodisk leads to a greater reduction in surface drag and heating on the body. The numerical results demonstrate pressure distributions and drag reduction for a flat-tipped spike attached to a blunted nose cone. This analysis found that a flat disk spike resulted in a maximum drag reduction of 72.5%. [ABSTRACT FROM AUTHOR]

The hypervelocity vehicle has a very high speed during flight and during this flight, the vehicle experiences very high wave drag on the body, with the highest pressure in the nose region of the vehicle. Therefore, it becomes necessary to reduce drag for safer and more economical flights. The retractable aero-spike is a simple and effective drag mitigation device, so it becomes imperative to use a suitable spike to increase its effectiveness. In this research, Numerical results on the effect of mechanical cut aero-spike at the stagnation point of a 60° half-angle blunt cone model in a hypersonic flow stream are presented. The commercial code of ANSYS fluent is used for the present numerical investigation. The two-dimensional Reynolds-average Navier-Stokes equation (RANS) was solved numerically using ANSYS Fluent. The k-ω two-equation turbulence model was used in this study. The length of the aerospike is taken by four different lengths to base diameter (L/D) ratios: 0.2, 0.5, 0.7, and 1.0. The numerical investigation discovered a drag reduction is about 20.6% (maximum mitigation) when using cut shape aero-spike in an axisymmetric 600 apex angle blunt cone. [ABSTRACT FROM AUTHOR]

C-wing design is one of many non-planar wings that can improve aerodynamic performance without compromising the aspect ratio of a typical aircraft. This paper presents and compares the aerodynamic characteristics of planar wings and C-wings with backward and forward swept configurations at transonic speed in terms of lift coefficient (CL), drag coefficient (CD), drag polar, and lift-to-drag ratio (CL/CD). The ONERA M6 wing was used as a benchmark in this study. The numerical analysis was conducted at a constant Mach number of 0.8395 with α ranging from 0° to 10° using the Spalart-Allmaras turbulence model. The results show that the Backward Swept C-wing (BSCW) delays the stall angle compared to the Backward Swept Wing (BSW). The Forward Swept Wing (FSW) and Forward Swept C-wing (FSCW) can operate at high α without showing signs of stalling. Furthermore, operating above the intersecting point, the C-wing configurations exhibit better drag reduction for a specific CL value compared to their respective planar counterparts. The CL/CD curves provide insight into the aerodynamic efficiency of the four wing configurations. The preliminary results indicate that both the BSCW and FSCW of this study can produce more lift and delay stalling α compared to their respective BSW and FSW counterparts. However, the CL/CD performance of both the BSCW and FSCW is comparatively lower than BSW and FSW, respectively, due to the interference of shock waves between the wing and C-winglet. This paper provides insight into the potential advantages and disadvantages of using C-wings in aircraft design. The findings of this study can inform future efforts to optimize aircraft performance by improving aerodynamic efficiency while maintaining similar levels of lift. [ABSTRACT FROM AUTHOR]

This paper presents a study of the design of a wing-mounted with a morphing winglet, along with its aerodynamic and structural analysis. The concept of span-wise morphing of winglets is proposed as it is an effective technology for enhancing aerodynamic efficiency and has the potential to replace conventional control surfaces. Further, the main advantages of variable span morphing winglets are the drag reduction that leads to an increase in range and endurance of the flight. The design includes a honeycomb core placed in between the skin of the winglet where span-wise morphing occurs to increase the structural integrity. Two actuators are used which are fixed at the rib of the winglet to carry out the span-wise morphing of the winglet. For aerodynamic analysis, ANSYS Fluent solver is used to investigate a flow field in a three-dimensional wing structure and to obtain lift/drag variations. It was observed that a 25% extension in span leads to a 4% increase in overall L/D. This shows that morphing in winglets can be a profound way to increase the aerodynamic efficiency of aerial vehicles [ABSTRACT FROM AUTHOR]

Vehicular exhaust emission is the most prominent cause of air pollution in India. Air pollution reduction to its minimum level is possible by switching from gasoline to electric vehicles. Since battery power consumption is a crucial aspect of a battery-electric car, lowering the aerodynamic drag force can decrease its consumption. In this study, a generic vehicle model named Ahmed body with a 35° rear slant angle was taken as a baseline model. FLUENT, a fluid flow component system of ANSYS, was used to simulate this baseline model at zero yawing angles via the k-epsilon turbulence model at velocities 20, 30, and 40 m/s. The result of the baseline model was validated from literature with a minimum difference of 0.35%. Drag reduction analysis was carried out to find the optimized model by placing an array of cylindrical vortex generators on top of the validated baseline model with diameters that varied in the range of 6mm to 12mm each at corresponding heights of 6mm to 18mm. The velocity contours and streamlines were studied to examine the wake region, and a maximum of 6.51% of drag reduction was found under investigation. Drag coefficient results of baseline and optimized model were applied to the real car under two road conditions. Flat road and 5% uphill were considered for calculating the percentage battery consumption reduction, and the best results were found as 3.97% and 2.25%, respectively. This drag reduction study in automobile engineering, especially for battery electric vehicles, can help reduce fossil fuel dependency. Thus, minimizing air pollution. [ABSTRACT FROM AUTHOR]

A micro air vehicle can be as small as 6 cm. Development is driven by military, research, and commercial purposes, with insect-sized aircraft that may be used in the future. The small aircraft allows for remote observation of hazardous environments, aerial photography, and robotics contests. The CFD simulation of fluid flow and aerodynamic performance of the dragonfly (Aeshna Cyanea) wing section was examined using FLUENT software at low Reynolds numbers (1000, 1250, and 1500) with various angles of attack (AOA) (0°, 5°, 10°). The numerical solver was based on the SIMPLE algorithm with Green-Gauss Node velocity pressure coupling. With increasing AOA, the mean lift coefficient increased while the drag coefficient decreased, resulting in improved propulsive performance. As the AOA rises, the gliding ratio increases in lockstep. The drag formation has some exciting outcomes. Because viscous effects are more significant at lower Re values, leading skin friction to be the primary contributor to drag reduction, the average drag coefficient in each case drops as the AOA increases. [ABSTRACT FROM AUTHOR]

In this study, the CFD simulation of fluid flow and aerodynamic performance of the dragonfly (Aeshna Cyanea) wing section at low Reynolds numbers (500, 750, and 1000) with various angles of attack (AOA) (0°, 5°, 10°) was analyzed through FLUENT software. The numerical solver employed was based on the SIMPLE algorithm, velocity pressure coupling with the Green-Gauss Node scheme. The triangular unstructured mesh simulation was employed as per finite volume discretization and observed that the mean coefficient of lift increased as the AOA increased, while the drag coefficient decreased, resulting in an enhanced propulsive performance with increasing AOA. The gliding ratio, increases monotonically as the AOA increases. The drag formation yields some intriguing results. The average drag coefficient in each case decreases as the AOA increases, as expected, because viscous effects are more prevalent at lower Re numbers, causing skin friction to be the predominant contributor to drag reduction. [ABSTRACT FROM AUTHOR]

The fluid in a turbulent flow is subjected to extensive amounts of frictional force and therefore leads to a great loss of energy due to drag. Base drag (drag generated in the fluid flow on exit when the flow is discharged in a sudden expansion duct in the wake region) is a contributor to total drag in high speed jets out of nozzles. Therefore, it is important to reduce base drag using some techniques, either active or passive. The base drag reduction techniques have applications in the aeronautical, aerospace, automobile and ship domain to name a few. Many researchers in the last two decades have conducted a number of experiments with passive methods and active methods to control and reduce base drag. Passive methods includes geometric modification at the exit of nozzle, for example, with slots, a vortex generator (VG), spoiler and splitter. The active base drag control methods used were suction creation, blowing of air jet, etc. The base pressure can be recovered using careful slot shape and placement optimization. A slot creation and modifications is one of the viable solution for the nozzle exit for a given Mach number to reduce base drag. The impact of the base drag on velocity for suddenly extended convergent-divergent nozzle using a passive control method (slot shape, width, and location) to control base drag has been analyzed and presented in this paper. The results from the CFD analysis suggests that the absolute velocity drastically changes from the inlet to outlet and its magnitude was high for the nozzle with a rectangular slot in the model. [ABSTRACT FROM AUTHOR]

Mathematical modeling is the main tool for studying complex gas-dynamic processes occurring in non-stationary conditions. It allows performing multiply research and development of engineering solutions with reliable accuracy. The search and development of controlling methods for the boundary layer of gas flows is a promising area of research, allowing intensify or reduce exchange processes in the boundary layer of power plants used in various fields of industry in our country, such as: energy, aircraft construction, shipbuilding. Method based on the use of the damping surface is a modern and effective control method. The damping surface effect is expressed in a decrease in the intensity of the turbulent vortices generation, which leads to an increase in the velocity in the boundary layer, a decrease in drag friction and heat transfer. The development of technology will make it possible to work out the engineering solutions for efficient and resource-saving energy. The studies were carried out using the ANSYS Fluent software package, which allows modeling the thermal and turbulent processes in the boundary layer using the k – ɛ turbulence model (realizable) with high accuracy. [ABSTRACT FROM AUTHOR]

The presence of a double aerodisk location changes the shock wave patterns and shock position. The research shows that the hemispherical spike reduces drag more effectively than the sharp spike by adopting a blunt spike on top of the hemispherical. When interacting with the hemispherical top, the supersonic flow creates a detached blow shock which will be converted to an oblique shock downstream with a small wave angle. For the computational study, the spike is taken of L/D=2 which is more than the critical length of the spike for freestream Mach 2.00. There are two hemispherical aero disks mounted on the spike. One is on the tip of the aerospike and the other one is at the location of flow separation of the spike having the same diameter. The research suggests that there is approximately 16% more drag reduction due to the hemispherical disk mounted at the location of flow separation on the sharp spike. These computational studies the combined effect of both the hemispherical disk mounted on the aerospike beyond critical length (for freestream Mach 2.00) as mentioned above. [ABSTRACT FROM AUTHOR]

A circular cylinder has been applied to the world of engineering with various geometries and is frequently placed in the stream of the fluid flow. The interaction between the flow and the cylinders causes drag, and at certain circumstances, causes lift also. The drag occurs due to the presence of pressure and friction on the cylinder surface. Therefore, in the present study, the researcher tried to investigate the flow behavior across three circular cylinders in a stagger arrangement placed in the airflow. The purpose of this study is to obtain drag reduction that occurs on the cylinder arrangement. This research was conducted numerically using Ansys Fluent® 19.1 and conducted in two-dimensional (2D) Unsteady RANS using the turbulence model of standard k-epsilon. In this study, the longitudinal distance (L/D) has four variations, i.e. L/D = 1.5; 2.0; 3.0; and 4.0 with a diameter of the cylinder (D)=25 mm. The cylinder arrangement is placed in a narrow channel with a square cross-section Wide x High x Long=300 mm x 300 mm x 600 mm, the flow Reynolds number in this study is set to be 2.4 x 104. The results showed that the distance (L/D) greatly affects the coefficient of drag of the circular cylinder in that arrangement. The smallest coefficient of drag on cylinders 1 and 2 occurs at a distance (L/D=3.0), while the smallest coefficient of drag on cylinder 3 occurs at a distance (L/D=2.0). [ABSTRACT FROM AUTHOR]

It is necessary to create a new technique to reduce drag forms employing natural materials such as fiber suspended and nanoparticles to meet the delicate hydraulic transfer standards. Individual and complex solutions of titanium dioxide (Tio2) and copper (Cu) nanoparticles were employed in this work to improve pipeline drag reduction. At varying flow rates, a closed-loop recirculation system (CLRS) was used in a series of studies. The selected drag reduction compounds were combined with a solvent (water) and manufactured at varying concentrations ranging from 50 to 1200 ppm using the ultrasonic bath method. Furthermore, using the X-ray diffraction (XRD) technique, morphological studies were carried out to discover microstructure structures of the complex agent. The highest percentage of drag reduction has been achieved by the complex solution of TiO2-Cu, at around 78% at 1200 ppm concentration and Re = 70770. [ABSTRACT FROM AUTHOR]

Flow control is an important topic because of its contribution in energy saving in piping system. The choice of control technique of flow is no less important to be applied in the right case. One of the impacts of this application is the efficiency of degradation time which can occur at any time. Therefore, the purpose of this study is to reveal the degradation time of two types of flow control. The research applied a piping system with a horizontal position. For the working fluid, it uses a mixture of nata de coco fibers for active control and spiral pipes for passive control with the slurries as the working fluid. Both pipes used were the three lobes spiral pipe and the pentagon spiral pipe with the average size P/Di 7. The results revealed that the active control had a variation of the drag reduction value with the increasing time indicating that degradation occurred while the passive control had a constant value. The results of this study are very important to determine the type of flow control that will be used according to the case handled and the results to be obtained. [ABSTRACT FROM AUTHOR]

When an autonomous underwater vehicle (AUV) sails beneath the water surface, the impact of various forces on the AUV's hydrodynamic performance is one of the key factors to be considered. A computational fluid dynamics (CFD) method is employed to numerically study and examine the parameters that effect hydrodynamic performance of an axisymmetric AUV travelling under water. The effects of flow on the AUV are quantified for various Reynolds numbers and submerged depths. It is assumed from past studies that the flow has a considerable impact on the AUV's lift & drag fluctuations, and the overall drag force increases with depth level and maneuvering becomes tough. This work focuses on study of flow past AUV where flow parameters like changing velocities, pressures and turbulence kinetic energies are studied. The analysis is carried out for AUV's at different angles of attack to study the required flow effects. The flow parameters like lift, drag, moment forces are evaluated to estimate the performance of the vehicle. The results obtained are in accordance with theory of aerodynamics where lift and drag forces are increasing with increase in angle of attack (AOA) from 00 to 100. The effect of aerodynamic stall is observed on further rise in AOA. Higher slope for lift coefficient is observed in comparison with that of drag coefficient. [ABSTRACT FROM AUTHOR]

The winglet is one of the best ways to reduce fuel consumption due to minimizing the drag generated at the wingtip. This study aims to determine the optimal winglet orientation and the influence of winglet Toe and Twist angle combination upon the aerodynamics performances of an airplane wing for Boeing 737 wings at Mach 0.78 in terms of lift-to-drag ratio. First, a sixty winglet models were drawn using SOLIDWORKS software, with various Toe angles (+10°, +5°, 0°, -5°, and -10°) and Twisted angles (-5°, 0°, and +5°) at (4) attack angles (0°, 3°, 6°, and 9°), with assumptions of the winglet Cant angle of 60°. A winglet span of 3.5 m was examined. Second, using analysis of systems Fluent, a computational fluid dynamics analysis of the wing-winglet arrangement based on the Boeing 737 airfoil on drag reduction at different attack angles was done. This analysis indicated that modifying the arrangement of the winglet's Toe and Twist angles can increase the aerodynamic performance at various attack angles. The lift to drag ratio value was calculated to decide which wing possesses the best aerodynamic characteristics. The best value of lift to drag ratio is equal to 18.67 at twist angle +5°, toe angle -5°, and AOA 3°. The lowest value of lift to drag ratio is equal to 5.23 at twist angle 0°, toe angle -10°, and AOA 0o, the percentage difference between the two model values equal 113%. [ABSTRACT FROM AUTHOR]

The aviation wing, owing to its complex behaviour in different loads and moves, is that sophisticated structure found above the aircraft Two processes, those concentrated loads or pressures on body and geometric discontinuities such as troughs or abrupt changes in its surface geometry, may produce stress concentrations in elastic body. There are numerous problems confronting the environmental effect element of aviation today. By simplifying design, weight is reduced by structural parts consisting composite materials. Drag reduction structures of the wing are necessary for substantial modifications for fuel efficiency. Improvisation is being carried out at every level since past, in order to prepare way for an effective fly mode in aviation. In this work, structural investigation diameter wing using composite material was undertaken. In order to build wing passenger plane with wing box included utilizing x wing profile, we have taken an approach. The wings are handled and drawled using CATIA-V5 modeling programmer using airfoil profiles. Ribs and spots match drawing geometry using CATIA V5 modeling software testing process is carried out using Finite Element Analysis technique utilizing ANSYS for ribs and spots corresponding wing with limits loaded at various points of the flight. The subsequent examination of the composite configuration is done alone and the final result is compared with aluminum. [ABSTRACT FROM AUTHOR]

Aerodynamic shaped truck and tractor body can improve the fuel economy by using external devices like boat tails, side skirts, and roof fairings over the cab, rear flaps and under flow carriages. This paper was focused on reduction of drag force on trucks for different aerodynamic shapes. The truck geometry was design in CATIA V5 R20 and simulation using ANSYS–CFX software. The flow around the truck was studied and investigated external drag reduction devices. The flow field analysis was performed for different velocities on each model. The result shows good agreement between wind tunnel and simulation. [ABSTRACT FROM AUTHOR]

Design optimization of car outer body is to bring best design solution to the real time application in order to achieve the efficiency, efficacy, strength, reliability and utilization. Growing advancements in automotive industry faced a problem to reduce fuel need without compromising an existing efficiency is a real challenge. Drag is the kind of pressure that forms behind the vehicle while the vehicle attains certain speed. It creates some space that attracts atmospheric air towards in it. This faster occupation of air pulls the vehicle backward which directly affects the vehicle fuel need. Drag coefficient and lift coefficient are the main factors to affect the movement of a car and its fuel standard. In order to reduce this drag and lift coefficient, designers pay much attention to study a vehicle structure that influencing drag and also focus on aero control add-on device like, under body diffusers which has major impact on fuel consumption, aero acoustics and steadiness of vehicles. Diffusers are the widely perform and most effective aerodynamic add-ons used both in competitive racing and passenger car vehicles that can be designed to increase the downforce and diffuse the high velocity air without generating much turbulence at the back end of the vehicle. The less turbulence formation allows the smooth flow at the back end which reduces negative pressure formation. The factors generating drag and detailed flow structure for various diffuser models were studied and proposed an effective way of reducing the drag in passenger vehicle using better aerodynamic diffuser model which helps to achieve higher mileage standards of car. [ABSTRACT FROM AUTHOR]

This study investigates the potential of multiple winglets mounted on a transonic wing. The investigation evaluates the reduction of drag coefficient due to presence of multiple winglets on the basic wing model. Numerical Experiments were adopted for these investigations. The commercial CFD solver ANSYS Fluent was used to perform the aerodynamic investigation. Four different models were evaluated based on the configuration. The first model is a non-winglet model, i.e., the base model. The remaining three models were the wings with the multiple winglets, i.e., 60-Winglet model, 75-Winglet model and 90-Winglet model. The differences in the model were based on the cant angle of the winglet. 3D RANS equation along with one equation Spalart-Almaras turbulence model was used for solving the flow past the wing models. The chord wise pressure distribution, pressure variation over the entire wing, coefficient of lift, coefficient of drag, lift to drag ratio were compared for all the cases. [ABSTRACT FROM AUTHOR]

In this work, a numerical investigation is carried out using the k-ω SSTSAS turbulence model to study the jet boat tail cavity effect on the SBAB wake topology and the resulting force coefficients. Three different jet boat angles, i.e., 2°, 4°, and 6°, are tested and compared against a straight cavity for their ability to modify the wake topology. With the inclusion of the jet boat tail cavity, a drag reduction of 11.27%, 15.73%, and 22.55% is achieved for the case of 2°, 4°, and 6° angles, respectively. This significant drag reduction magnitude is because of the increased base pressure and transformation of the asymmetrical wake into a symmetrical wake. Due to the underbody flow acceleration in a cavity's presence, the lift coefficient is negative and increases with the jet boat angle. Also, the wake's temporal nature is analyzed by performing an FFT (Fast Fourier Transform) of the lift coefficient to realize the contribution of the wake unsteadiness to the force coefficients. From the FFT, the strength of the wake unsteadiness decreases continuously with an increase in the jet boat angle. This temporal behavior observation interprets that the inclusion of the cavity reduces the chaotic nature of the wake. [ABSTRACT FROM AUTHOR]

Aerodynamic drawbacks of intercity bus profile have become a concern since it generates a considerable large value of drag coefficient. The study aims to propose some options to improve the aerodynamic profile of the external body shape of a bus to produce a better aerodynamic performance. The adopted aerodynamic profile improvement from current aerodynamic devices from other types of vehicles has chosen to modify the external shape of a bus. The study presents the numerical value of the resulting drag coefficient and lift coefficient for each proposed bus profile modification. It compares the resulting value from the original bus model to other modified models The visual comparison of the resulting pressure coefficient around the bus, velocity contours, and resulting turbulence kinetic energy assists the readers to better understand the aerodynamic behavior of the modified bus profile. The overall comparison indicates that combining all proposed additional aerodynamic devices and reshaping the bus profile largely benefits in the drag reduction compared to the original bus model, which leads to 0.09 point of drag reduction. Each modified part positively contributes to better airflow around the bus model. [ABSTRACT FROM AUTHOR]

A group of vehicles traveling in a formation generally experiences more complex aerodynamic behavior. The phenomenon becomes more intricate when a crosswind is considered. The study investigates the aerodynamic response of four different vehicle formations by considering crosswind conditions and employing a modified reference model. The study examines the resulting aerodynamic response in terms of drag coefficient, lift force coefficient, side force coefficient, and pressure coefficient around the vehicles. The first case identifies the vehicle travel in four types of formation with the absence of crosswind. The second case investigates when the vehicle formation travels with the interference of crosswind, producing a 20° yaw angle of the incoming flow. The results indicate that vehicles in the first row relatively generate a lower drag coefficient compared to other vehicles. Two vehicles running at the same row generate an opposing value of side force coefficient when traveling without crosswind. The vehicle positioned at the rear part of the formation benefits more in terms of drag reduction. The presence of crosswind considerably increases the aerodynamic coefficient in nearly all vehicles in the formation. [ABSTRACT FROM AUTHOR]

The selection of friction reducer (FR) types in the slickwater is critical to reduce friction loss, achieve a high drag reduction rate, and to ensure less formation damage while ensuring the porosity is at a premium. Numbers of research have been done to study the FRs mechanism, thus providing a generally accepted qualitative view of the process. However, despite the extensive use of FRs, the process mechanism brought by the FRs are not fully explored. The paper reviews the FRs mechanism, FRs characteristics, and the advanced research proposing research directions of FRs. Moreover, the proposed methods for the development of FR's standard testing procedure are also discussed. [ABSTRACT FROM AUTHOR]

Spoilers and wings are integral aerodynamic devices used in automobiles to reduce drag or to increase downforce, as preferred. Rear wings help high-speed cars to increase the performance and maintain stability while racing. In road-cars with spoiler, the reduction in drag can result in an increase in the fuel economy. It is seen in the various literature that the calculated use of these devices can be used to improve the acceleration and braking of a vehicle. This project focuses on selecting the best automotive wing by analyzing various existing ones both numerically and experimentally using CFD and wind tunnel testing. The CFD simulations concluded that the NACA 4412 (at 5o) produced 41% increase in downforce than stock rear wing. The wing prototypes of the 3 airfoils are 3D SLA printed and are then fixed with the scaled down model of the race car. The scale model is set up in a wind tunnel and force measurements are made. The best wing design NACA 4412 (at 5o) that meets the objective is then selected and made into an actual scale model and fitted on the rear of a Opel Astra and appropriate force measurements are made. The results support the CFD results to some extent and show that increased downforce and drag for braking is achieved. [ABSTRACT FROM AUTHOR]

In the present paper, the effect of the change of position and change of dimension (modification) of the landing gear on the drag reduction of the fighter aircraft have been studied. Modeling of the landing gear of model 1 to model 4, have been done using Catia V5 and numerical simulation have performed using CFD to evaluate the coefficient of drag, velocity, turbulence intensity and static pressure. The modification of landing gear results in a reduction of the drag coefficient. The drag coefficient for model 1 was found 1.37. Whereas, for model 4 the drag coefficient was reduced to 0.46. The maximum drag reduction was achieved for model 4 is about 66%. The drag reduction of fighter aircraft would directly affect the fuel consumption, rang, and endurance of the fighter aircraft. [ABSTRACT FROM AUTHOR]

The major challenge in aerodynamics is the reduction of drag for high-speed vehicles. Re-entry vehicles usually travel at hypersonic speeds, because of this, they experience high temperature and drag force. One of the ways to reduce the heating and coefficient of drag is by using spike. In the present study we have numerically investigated the aerodynamic performances of a blunt body with sharp spike and hemispherical spike with different length to base diameter ratio using ANSYS fluent. We have compared the performance of the bunt body with and without spike. Density based solver and explicit method have been used as it is most preferred for high-speed flows. Simulations have been carried out at three different Mach numbers 4, 5 and 6. Effect of semi vertex angle of the sharp spike is also studied. Results are validated with the available literature. It is observed that drag coefficient increases with increase in Mach number, semi vertex angle and decreases with increase in L/D ratio. It was also found that both drag coefficient and Heat flux were minimum for hemispherical spike when compared to others. [ABSTRACT FROM AUTHOR]

The design of a vehicle flying at supersonic and hypersonic velocities plays a crucial role in the performance and efficiency of the vehicle, because at these velocities there will be shock waves dominating the flow. If the vehicle is designed in such a way that its deflection angle is less than the maximum deflection angle, then the shock wave will be attached to nose of body, which increases the heat load on the vehicle. Therefore, the vehicles, which fly at these speeds, are designed in such a way that a better thermal management is achieved. To satisfy this requirement, the vehicle's body is designed as blunt body, which will have the defection angle greater than its maximum deflection angle so that the shock wave will be a detached one and it will not be in contact with the body. This reduces the heat load on the body and better thermal management is achieved. Though better thermal management is achieved with the blunt body, the drag experienced by the body will increase, as detached shock wave acts like a cushion between the body and the air stream. In order to reduce the fuel consumption and to achieve greater efficiency, the drag has to be reduced. In this work a Breathing Blunt Nose along with aflat-faced aero-disk is considered for study and investigations are done varying angles of attack and the resulting drag, lift and heat flux have been measured. Due to the relief offered because of breathing of high pressure flow and flow being ejected in the base region, the shock wave will become weaker. In the present study, a Breathing Blunt Nose with a Flat-faced Aero-Disk(BBN-AD) and a Simple Blunt Body with Flat-faced Aero-Disk(SBN-AD) are considered and a comparison has been made. Flow field around the body has been visualized by streamline contours. [ABSTRACT FROM AUTHOR]

Boundary layer control on a surface streamlined by high-velocity gas flows is an important task in modern technology. There is a wide range of active and passive flow control methods used to reduce frictional drag, heat transfer, turbulization, mainly in incompressible turbulent boundary layers. The development of science and technology does not stand still, and in modern conditions, given the need to improve the efficiency of equipment, reduce energy consumption in production and fulfill a number of tasks to modernize the energy complex, set by the Ministry of Energy, in the draft energy strategy of Russia for the period up to 2030, it is necessary to develop new and efficient ways of managing the boundary layer to create efficient and resource-saving energy. The paper proposes a method for mathematical modeling of turbulent transfer on a damping surface. The method allows one to study the effect of the damping surface on the exchange processes occurring in the boundary layer in the range of Re numbers from 1 · 105 to 4 · 107. [ABSTRACT FROM AUTHOR]

The effect of rough surfaces models on the airfoil performance has been investigated experimentally for selected airfoil model (symmetrical with four-digit NACA0012) and the flow is presented for six models of rough surface (Mo.1,2,3,4,5, and 6) as (40, 50, 60, 80, 100, 120 and 200 holes per inches) respectively. Models were investigated with different angles of attack (0°, 2°, 4°, 6°, 8°, 10°, 12°, 14°, and 16°) at chord Reynolds number (1.86x105). pressure, mean velocity profile, lift and drag coefficients curves for the airfoil are presented as a result. The most effective rough surface model is (Mo.6), by comparing the result with smooth surface, It show a decrease in drag about (18%) and an increase in lift curve with (12%) for NACA0012 for angles of attack range from (0° to 16°). [ABSTRACT FROM AUTHOR]

This paper suggests and discusses different drag reduction methods for two-phase horizontal flows through pipes. Two-phase flows are the simplest and most common among the multiphase flows, and have a great importance in real life. Drag reduction can be achieved through the addition of drag reducing additives or agents in the flow system and such method is known as additive method. Drag reducing agents include solid suspensions, polymers and surfactants. Two types of additives exist, soluble and insoluble additives. Insoluble additives include solid suspensions and soluble additives include polymers and surfactants. Nanofluids are also used as drag reducing agents. Combined methods of drag reduction also exist where two different drag reduction methods are used together to achieve drag reduction. The drag reduction is well achieved through solid suspensions, polymers, surfactants and nanofluids. It was also found that combined methods of drag reduction showed more drag reducing ability than methods used separately. From an environmental perspective, the biopolymers are more effective than synthetic ones due to some desirable properties of biopolymers such as cheap, non-toxicity, renewability, bio-degradability, stability, biocompatibility and easy availability. [ABSTRACT FROM AUTHOR]

High power consumption in piping system due to high pressure losses in a turbulent flow has been recognized as a critical problem occurring to fluid flows in various industrial piping systems, including crude oil transportation in the oil and gas sector. To solve the problem, a drag reducing agent (DRA) is added into crude oil flow for improving the pumping efficiency. One of most technically effective, low costs and well-known DRA is anionic surfactant. Thus, the purpose of this study is to investigate the pressure drop reduction by adding anionic surfactant sodium lauryl sulphate (SLS) at different concentrations into crude oil flow in a pentagon spiral pipe. Moreover, our study also reveals the drag reduction mechanism by showing its velocity profile by using computational fluid dynamic (CFD) method. Effectiveness of the DRA was comparatively observed in a pentagon spiral pipe with 10.8 ratio of diameter (P/Di) and in a circular pipe with 4 mm inner diameter. Meanwhile, CFD method to reveal its velocity profile was done using ANSYS-Fluent. Then, a certain concentration of anionic surfactant SLS is observed to actively reduce friction factor. [ABSTRACT FROM AUTHOR]

The paper provides a brief overview of recent computational studies of flow and heat transfer control by rotary oscillations of an infinite circular cylinder at a relatively broad set of imposed frequencies and amplitudes [1, 2]. A study for a previously unreachable high subcritical Reynolds number Re = 1.4 × 105 showed that the efficiency of this control method increases with Re concerning the issue of drag and lift reduction. High-frequency oscillations even lead to around 90 % reduction of the drag. However, the benefits for heat transfer enhancement is not that obvious as the bulk Nusselt number shows only small variations. At the same time its angular distribution around the cylinder becomes much more homogeneous due to oscillations which practically can prevent local overheats. [ABSTRACT FROM AUTHOR]

Design optimization of the vehicle has been an integral part of Vehicle Aerodynamics. The reason so much heed is given to this research area is due to the ever-growing concern of detrimental effects of fuel on the environment. This paper aims to optimize the shape of auto-rickshaw which is one of the most widely used vehicles in India. Being the developing nation, people use auto-rickshaw because it is economical which makes it essential to modify the design to reduce drag. This, in turn, improves the fuel efficiency of the auto-rickshaw. The impact of the addition of diffuser at the underbody along with varying slant angle at the rear side to provide boot area is studied. The modifications are done on CATIA V5 followed by investigating the coefficient of drag on ANSYS Fluent. [ABSTRACT FROM AUTHOR]

Tuk Tuk is a common vehicle used by many people in various countries. The vehicle is designed for low and medium speeds due to the usage of small capacity engines for higher mileage purposes. The improvement in aerodynamic performance is the only way to improve the efficiency of the vehicle. To know about the aerodynamics, the present study focuses on the study of flow over the considered vehicle via drag with moment generation and flow visualizations. The results show the modifications done to the vehicle results in drag reduction [ABSTRACT FROM AUTHOR]

A method for calculating the main parameters of a multistage turbomolecular vacuum pump (TMP) providing the main pumping parameters, including the ultimate pressure, the pumping speed, and compression ratio in the molecular gas flow regime has been developed. As a result of the calculation of the main parameters of multistage TMP according to the proposed method, the pumping curve of the drag stage was obtained. The pumping curve of TMP was also obtained taking into account the influence of the main parameters of the drag stage in the molecular regime of gas flow. [ABSTRACT FROM AUTHOR]

Supercavitation is a hydrodynamic behavior, which leads to a drastic reduction in hydrodynamic drag by allowing the bodies to travel inside a self-generated bubble of water vapor or gas. The world's major navies are developing entire arsenals of totally new high-speed underwater weapons based on the physical phenomenon of supercavitation. This research concentrates the shape of the cavitator optimization by means of numerical investigation. The shapes of the axisymmetric cavitators like disc, hemispherical, conical and edged double conical were considered with the same diameter. The modeling and CFD analysis were conducted in ANSYS Fluent 16.0. The RNG K-epsilon turbulence model used to evaluate the performance of various shapes of the axisymmetric cavitators. The Contours of Density (Mixture), the Contours of Volume Fraction (Water) and the Contours of Volume Fraction (Vapor) considered for comparison and resulted length of supercavity is used to optimize the shape. [ABSTRACT FROM AUTHOR]

In the growing age, scientists discovered new technology for fish cooling, using ice slurry. Having a Globural shape, Ice Slurry have better quality of cooling than any other dendritic ice. In general, when the ice slurry flow is not sufficiently high the particles will not be maintained in suspension. The purpose of this study was to examine the drag reduction as the ice slurry is released using a spiral pipe. This research investigates two variation of pipes: spiral pipe and non-spiral pipe, with hydraulic diameter of 1 inch and pitch/diameter ratio 6,7. The working fluid is mixture of freshwater with 15% concentrations of glycol. The ice fraction varying at 3%, 6%, 9%, 12% and 21%. Visual observation were also done to investigate the system performance and the rheology of ice mud particles in the spiral pipe made of transparent acrylic. The drag reduction occurred significantly in the flow of ice slurry in a spiral pipe. Spiral pipe with a difference of p/d ratio also produce different flow speeds. It can be seen that the use of spiral pipes to run off ice slurry can significantly reduce the resistance that occurs to the fluid. With the proof of the drag reduction of the spiral pipe flow when compared with the round pipe up to 32% in the ice fraction 6% and Re 4438,8. [ABSTRACT FROM AUTHOR]

Pollution is a main focus in the status quo of global warming. One of those main contributors is the shipping industry. Massive usage in fuel oil by the ship around the world, especially the container and tanker ship produce more than 40% of total world pollution. Many research has been done to solve this problem, such as main fuel conversion also by increasing the efficiency of the ship itself. One of those methods which increasing the efficiency is the air lubrication method by increasing the drag reduction of the ship. In this research, we used the device called as Winged air induction pipe (WAIP) to lubricate the bottom of the ship. This device using foil to create bubbles by making low pressure area in the upper area of the foil which will suck the atmospheric air through the pipe and trap those air inside the flow which will became bubbles. In the previous research the same method has been done, but the explanation about how the various configuration of chord length and the effect of viscous resistance will affect the creation of the bubbles were not explained yet. In this research, we used numerical simulation by using ANSYS CFD-Fluent with k-w SST (Shear Stress Transport) method. At the end the error occurred only 1,49 % compared with experimental research done by previous studies. This research also used the same NACA 653−618 which has been used by previous study within the addition of variation of the chord length of the foil. At the end of the research, there is a tendency between viscous resistance and net power saving by the device, which is at 6% of total power saving. [ABSTRACT FROM AUTHOR]

In marine industries, especially in the maritime industry still using fuel oil massively. It produces a big amount of pollution to the atmosphere and becoming one of the main factors the global warming is happening. Increasing the efficiency of the energy that has been used in the ship is one of the solutions to overcome the problem. Winged Air Induction Pipe (WAIP) is a device that used, it will create micro-bubbles to coat the keel of the ship by pulling air through the induction pipe by the negative pressure produced by the hydrofoil. The different placement of the foil will also give the different results of the drag reduction experienced by the plate located after the hydrofoil. This research will see the different results of the drag reduction caused by different variations of angle of attack and chord length on foil NACA 653−618. One of the ways to see how those customization and setup affect the result is by using the k-ω SST (Shear Stress Transport) model in numerical simulation. By using this setup error on numerical results at 1.93% by comparing to previous experimental studies. The angle of attack of hydrofoil that gives the most efficiency for the ship. The drag reduction in this research can give 3% of efficiency on the model of the ship. [ABSTRACT FROM AUTHOR]

The growing interest to produce biofuel from vegetable oil has increased demand for crude palm oil (CPO) as a potential source for biofuel production. The common problems encountered in industrial processes through piping system are cloudiness and high consumption on pump power due to high drag in CPO flow. Tween 80 (T80) as nonionic surfactant commonly used to reduce the cloud point. The objective of this study was to more wide investigate about T80 in several concentrations into CPO flow in pentagon spiral pipe to reveal the drag reduction impact. The test pipes were the pentagon spiral pipe with diameter ratio P/Di 10.8 and circular pipe with inner diameter 4 mm. The circular pipe was used comparison for drag reduction prediction. The effectiveness of drag reduction effect was analyzed by measuring of pressure drop at two pressure tap points. The results showed that T80 concentrations have an important impact on drag reduction effect and pentagon spiral pipe have higher drag reduction effect than circular pipe. [ABSTRACT FROM AUTHOR]

Surface roughness is known to have dominant impacts on a fluid flow, especially flows with high pressure drops such as the flows of crude palm oil (CPO). This study aims at analyzing the impacts observed in a pentagon spiral pipe to optimize energy consumption in CPO transport. In this study, a steady-state numerical analysis is performed in ANSYS-Fluent 19.2 software. Practically, a numerical analysis is conducted by simulating a pentagon spiral pipe using Navier-Stokes equations. Then, the effects of relative roughness and Reynolds number on drag reduction are investigated in the simulation. Looking at results of the simulation, this study highlights the importance of modelling the behavior of surface roughness effects at different temperature levels to discover better drag reduction impacts for improving efficiency in energy consumption for transporting CPO. [ABSTRACT FROM AUTHOR]

Drag reduction on the ship with an air lubrication method using microbubble started since the late 19th century. However, its application in industry obstructed because the net power-saving only reach 0-5% in the consequences of the energy needed by the air compressor to blow the air to the keel of the ship. A new device named Winged Air Induction Pipe (WAIP) uses the negative pressure produced by angled hydrofoil to suck atmospheric air into the water generating bubble without compressor needed. Interaction between the diameter of the pipe and the hydrofoil chord length influence the drag reduction occurred. The Computational Fluid Dynamics (CFD) approach by 'volume of fluid' model and SST k-ω turbulence closure model on 2D boundary condition, used to observe how these two variable affects the result. In the discussion, the correlation between those variables gives the maximum efficiency to the ship. On the optimum range, drag reduction can reach 9.5%. [ABSTRACT FROM AUTHOR]

High power consumption in piping system due to high pressure losses in a turbulent flow has been recognized as a critical problem occurring to fluid flows in various industrial piping systems, including crude oil transportation in the oil and gas sector. To solve the problem, a drag reducing agent (DRA) is added into crude oil flow for improving the pumping efficiency. One of most technically effective, low costs and well-known DRA is anionic surfactant. Thus, this study aims at investigating the reduction of pressure drop by adding anionic surfactant sodium lauryl sulfate (SLS) at different concentrations into crude oil flow in a pentagon spiral pipe. Effectiveness of the DRA is comparatively observed in a pentagon spiral pipe with 10.8 ratio of diameter (P/Di) and in a circular pipe with 4mm inner diameter. This research particularly highlights the application of pentagon spiral pipe to provide the maximum drag reduction performance for crude oil flow. Then, a certain concentration of anionic surfactant SLS is observed to actively reduce friction factor. [ABSTRACT FROM AUTHOR]