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The energy released during the bubble collapse process is used for medical and industrial purposes. The present study investigates the effects of electrohydrodynamic force on the collapse phenomenon near the rigid wall and the enhancement of the collapse energy. A solver in the OpenFoam open-source code is developed based on the volume-of-fluid model, in which the effects of compressibility, energy transfer, and electrohydrodynamic force are included. The developed solver is validated against the available experimental data, and a good agreement is seen. The effects of an electric field on the bubble collapse for the range of the electrocapillary number (CaE) of 0–5.76 and normalized wall distance (γ) of 0.8–2.0 are investigated. The results indicate that the bubble is deformed due to the presence of an electric field, and the values obtained for the maximum velocity and pressure are 33 and 35 times the state without the electric field at γ = 2 and CaE = 5.76, respectively. Also, due to the increase in velocity, the maximum shear stress on the rigid wall is increased up to seven times in the absence of the electric field. Therefore, the jet force obtained from the bubble collapse can be enhanced by applying the electric field in the continuous phase fluid. Also, the correlations are proposed to estimate the jet velocity, pressure, and wall shear stress of bubble collapse in the presence of an electric field.

One of the highly efficient sources of renewable energy is the Ground Source Heat Exchangers (GSHE). Thermal interaction effects between boreholes cause a decrease in the efficiency of GSHEs. In the present study, the effects of the distance between boreholes, soil properties, grout heat conduction coefficient, and boreholes’ arrangement are investigated on the outlet fluid temperature in the GSHEs. The Finite Line Source (FLS) model is coupled with the Simplified Thermal Resistance-Capacity Model (STRCM) and a transient modified model called FLS-STRCM is developed. The FLS model considers the thermal interaction between boreholes while the STRCM model solves the flow field inside the boreholes. The obtained results of the FLS-STRCM are compared with the transient results of Computational Fluid Dynamics (CFD) simulations and available experimental data. To simulate the heating and cooling cycles of a building, the present model of GSHE is coupled with the water to air heat pump in the TRNSYS software. The available models of GSHEs in the TRNSYS software are not capable of considering different arrangements of boreholes. However, the present model, in addition to the transient simulation of GSHEs, can examine any desired layouts of boreholes. The results of the present model show that for a set of 6 boreholes in a rectangular arrangement, a reduction of the distance between boreholes from 7 m to 3 m results in 2.8% changes in the average temperature of outlet fluid. Also, the investigation of soil and grout properties shows that the soil properties has a dominant effect on the outlet fluid temperature. Considering the computational time and the acceptable accuracy of the presented model compared to the CFD methods, the FLS-STRCM model can be employed for the engineering applications in the construction of the GSHE system and the long-term simulations.

Rotating Vortex Rope (RVR) resulting from flow instabilities inside draft tube affects the hydraulic turbine's efficiency and wear. Among the passive and active RVR mitigation methods, the water injection method has been widely investigated lately. The present research focuses on the dynamics of RVR mitigation using the water injection method and the optimization of exergy loss during the water injection. The numerical simulations are performed using a reduced turbine geometry consisting of one stay vane, two guide vanes, one runner passage by applying periodic boundary conditions at side boundaries, and a complete draft tube. The pressure fluctuations, velocity field, and the RVR structure are well captured using the Shear Stress Transport - Scale Adaptive Simulation (SST-SAS) turbulence model. The results of the local swirl number during the load variation show that the onset of flow instabilities and RVR formation are created due to a decrease of the axial momentum below the runner cone. The required axial momentum flux of water injection is calculated for a stable swirl number and the local minimum ratio of dimensionless loss to the pressure recovery factor. The numerical results show that the rotating and plunging components of the pressure fluctuations inside the draft tube reduce during the water injection. The pressure recovery of the draft tube improves. The dynamics of RVR mitigation are visualized using λ2 criterion and the spectrogram of pressure probes on the draft tube wall. An optimum water flow rate and jet velocity for a fixed axial momentum are proposed. The results show that a water jet with a large radius and low velocity is more effective to mitigate the RVR and minimizing the draft tube losses.

In this paper, water droplet behavior and its removal process in the anode gas flow channel (GFC) of a proton exchange membrane fuel cell (PEMFC) with partial blockage are numerically investigated using a three-dimensional volume of fluid model. The governing equations are solved using the finite volume method. The effects of the droplet emergence location ( $$\alpha )$$ , blockage ratio ( $$\beta )$$ , longitudinal ratio ( $$\gamma )$$ , contact angle ( $$\theta )$$ and current density on the water management characteristics, such as droplet shape, removal time, instantaneous and time-averaged pressure drop and water coverage ratio (WCR), are studied. Researchers have already considered the blocking effect on the PEMFC performance without considering the water droplet movement, but the results of the present study show that blocking the GFC has a significant influence on the behavior of water droplet and water management characteristics. As a result, in some cases, pressure drop fluctuation is increased up to 140% in the anode channel. It is also found that by decreasing $$\alpha $$ and increasing $$\beta $$ and $$\gamma $$ individually, the removal time was decreased and the pressure drop increased. Furthermore, our results showed that blockage in the anode channel has a little effect on WCR.

Rotating Vortex Rope (RVR) has been a matter of focus for years due to the major effects on hydraulic turbine’s efficiency. The exact procedure of RVR formation is still vague. The present research focuses on the dynamics of the RVR formation during the load variation employing transient numerical simulations. Two different geometries including the full geometry and the reduced one, which consists of one stay vane, two guide vanes, one runner blade, one splitter blade and full draft tube, are considered. In order to capture the transient swirling flow features inside the draft tube, the Shear Stress Transport-Scale Adaptive Simulation (SST-SAS) model is utilized to approximate the turbulent stresses. The pressure results inside the draft tube agree well with the experimental measurements. Moreover, the velocity results show the central low-axial-velocity and high-tangential-velocity region in the draft tube properly. The flow structure is visualized using λ2 criterion. The dynamic of RVR and the physics behind the RVR formation are investigated during the load variation. The results indicate four flow regimes with different characteristics during RVR formation. The first flow regime is a stable swirling structure occurring at Best Efficiency Point (BEP). The second flow regime occurs at the beginning of the load variation where signs of flow instabilities appear. These instabilities are temporary and washed down by the upstream flow. Expanding the instabilities and creating the vortical structures in the draft tube are the important flow features in the third flow regime. The fourth flow regime is the presence of a developed rotating rope occurring at the Part Load (PL) condition. The flow regimes differ according to the size and shape of the stalled region during load rejection inside the draft tube cone. They also reveal that despite some shortcomings, the reduced model is reliable to simulate the RVR transient formation. The full geometry simulations could be also applicable for practical problems provided that the modified time step is slightly greater than the main blade rotational angle is used.

Accumulation of ice particles inside the pipes of an ice slurry refrigeration system is a problem that should be avoided to ensure the efficient performance of the system. In the present research, ...

This research presents a numerical investigation of two-phase flow during the expulsion of entrapped air in a non-confined pipe. A modified version of the volume of fluid (VOF) approach is employed...

Nucleate boiling is an important part of pool boiling process. Heat transfer from the microlayer plays a considerable role in heat transfer to the fluid. The axisymmetric assumption of the microlayer for a horizontal surface needs to be evaluated for an inclined one. In this study, the effect of surface orientation on the microlayer thickness and the heat transfer rate are investigated numerically. The governing equations are simplified employing scaling analysis. The results for the microlayer thickness, the heat flux and the total heat transfer rate for the heated surface are obtained and presented. The asymmetry of the microlayer increases as the surface inclination angle varies from horizontal to vertical. Even though, the driving force due to gravity in the microlayer is negligible, however its effect on the macro region changes the microlayer parameters. The results show that the maximum microlayer heat transfer rate for the vertical surface increases by 28.8% compared to that for a horizontal surface. The proposed model, which is capable of evaluating the microlayer thickness and its surface heat transfer rate, can be employed as a surface boundary condition in the macro region simulations of the nucleate boiling.

In this paper, a parametric study of anode channel clogging of a proton exchange membrane fuel cell (PEMFC) is presented using the numerical volume of fluid method. The droplet size distribution in the present research is considered close to reality. Therefore, three droplets with different sizes are initially placed on the anode channel wall. The droplet sizes are obtained based on the distribution of the saturated liquid water along the whole channel under a specific working condition and the amount of condensed water in the channel, using the PEMFC code. Finally, the dynamic behavior of the droplets is investigated and compared to that of a single droplet with the same total volume. Numerical results show that, in the case of three droplets, the droplets coalesce during the removal time and form a larger droplet. Also, the droplets gradually spread over the channel walls and eventually reach the upper corners of the channel and form liquid slugs. Then, the slugs move slowly toward the channel outlet, and after a while, their shapes and positions are fixed and cause the channel clogging. Changing the number of droplets does not significantly change the time of channel clogging. The numerical results show that the time-averaged pressure drop of three droplets is about 85% less than that of a single droplet.

In modeling the drying process of a skim milk droplet subjected to a hot gas flow, ignoring the effect of solid particles in reduction of evaporation surface before the crust formation and porosity variation within the droplet, causes the predicted surface temperature of droplet deviate from the experimental values. In the present study, a new drying model is developed in which the effects of variable porosity within the droplet as well as the reduced area of the evaporation surface due to the presence of solid particles are accounted for. Based on this model, a Finite Volume code is developed to calculate the droplet porosity at all drying stages and also taking into account the effect of solid particles in reducing the evaporation area of the droplet by calculating the diffusion coefficient of porous medium. Using this model leads to a better prediction of droplet temperature with a maximum error of 2% compared to experimental results. This model also has a good prediction of droplet mass reduction with an average error of about 10%. Also, a parametric study is performed to investigate the effect of the principal parameters such as air temperature, air velocity and droplet initial diameter on the drying time and morphology of obtained dry particles. Peclet number is a criterion for determining the morphology of dried particles. Numerical results show that with increasing the hot air velocity and temperature, the Peclet number increases but the initial droplet size does not have much effect on the Peclet number. Based on this observation a new correlation is introduced between the Peclet number and the characteristics of the dryer air flow.

The need to have an efficient oil-water separator leads to improve and optimize the hydrocyclones. One way to improve the efficiency of a deoiling hydrocyclone is using air injection. In the present study, the effects of air injection on the three-phase flow field, oil droplet distribution, separation efficiency, and the working principles of deoiling hydrocyclones are investigated using the Eulerian-Eulerian multi-fluid model. The numerical results of two and three-phase flow are in good agreement against the experimental data. The oil core which is formed at the center of the deoiling hydrocyclones disappeared due to the air injection. The injected air creates an air-core inside the deoiling hydrocyclone and flows out through the overflow. The results show that the air injection increases the migration velocity of oil droplets and the length of the reverse flow region, leading to the enhancement of the separation efficiency. The air injection also increases the turbulence level and consequently increases the breakup rate of the oil droplets inside the deoiling hydrocyclone with air injection. Therefore, the air-liquid ratio and the injected bubble diameter should be regulated to increase the efficiency of the air-injected deoiling hydrocyclone. The results of different air injection diameters show that the small injection diameter is preferable due to the more penetration inside the deoiling hydrocyclone and increase the reverse flow region. The simulation results show that the air injection with bubble diameter of 42 μm increases the hydrocyclone efficiency up to 95.6%.

An uncontrolled rapid filling or discharging of a pipeline can create compressed air columns in an urban water supply or sewage system. The expulsion of entrapped air out of pipelines is considered as one of the most destructive phenomena. Generally, the air valves are mounted and used to release the air from the pipe. Any failure of the air venting system may lead to a pressure surge inside the pipeline and even damage to the water systems infrastructure. Most of the investigations of multiphase flow during a rapid filling are limited to small distribution systems due to high computational costs. The aim of the present research is to develop a 1D-3D coupled model with the capability to handle multiphase flows. The effects of air pocket length, orifice size and upstream pressure on the flow field and maximum pressure surge inside the pipe are investigated. The classical water hammer equations are solved for the 1D domain using the Godunov scheme while the rest of the system is simulated using the Volume of Fluid (VOF) method. The coupling between 1D and 3D domains are handled using the developed boundary conditions based on flow characteristics. The results of the numerical simulations are compared with available experimental data. The obtained results show that the model can predict the features of the two-phase flow inside the pipeline during a rapid filling. The required computational time decreases by a factor of 4 compared to 3D simulations. This gives the possibility to investigate large scale water distribution or drainage systems.

In this paper, a new algorithm of image reconstruction for electrical capacitance tomography (ECT) is introduced. The algorithm is developed based on the analogy between image reconstruction and inverse heat conduction problems. The algorithm determines the conductivity value and the boundary of an unknown object inside a circular domain. For this purpose, the governing equations are discretized using finite volume method, and a boundary fitted mesh is employed to capture complex geometries. Five different case studies are investigated to ensure the reliability of the proposed method. Calculated results showed that the presented method could find any smoothed object in a few iterations. The accuracy of obtained results and the lower calculation time of the presented algorithm represent a new applicable and reliable algorithm for ECT image reconstructions.

In this study, the deposition rate of asphaltene particles is modeled considering the asphaltene particles interactions using the population balance approach. The modeling consists of three sub-models: (1) The distribution of the asphaltene particles along the pipe, (2) The transfer of asphaltene particles from the bulk to the wall using the Eulerian approach, (3) Adhesion of asphaltene particles to the wall. The most important transport and deposition mechanisms, including the drag, molecular diffusion, eddy diffusion, turbo-phoresis, and thermo-phoresis, are considered in simulations. To calculate the adhesion velocity, the concept of the adhesion coefficient is employed for particle bins. The results of adhesion velocity show that the particle size, surface temperature and fluid velocity strongly affect the adhesion of particles. Therefore, accurate modeling of the adhesion step considering the interaction of the particles has significant effects on the prediction of asphaltene deposition rate. Furthermore, the effects of changing the process conditions including the surface temperature, fluid velocity and asphaltene concentration on the deposition rate and size distribution of particles, are investigated. The results showed that considering the particle size distribution and particles’ interaction reduces the error of numerical simulations. The developed framework can be employed for further investigation of asphaltene deposition using multi-fluid approaches.

Radiant cooling panels are believed to be of considerable energy saving potentials and can be employed as new cooling devices in HVAC systems. Even though the popularity of radiant cooling systems grows, particularly for cooling and heating commercial buildings, the condensation problem limits their application. The present research is conducted to introduce and evaluate a new method to control the condensation problem in the Ceiling Radiant Cooling Panels (CRCP). A dehumidification coil is integrated with CRCP in order to regulate the water condensation and remove the latent heat load. To evaluate the capability of the new model, the performance of the system was numerically investigated in a sample office, for different wall insulation and room configurations. The results showed that the integrated cooling coils enhance the natural convection heat transfer and remove the water vapor from the space. Therefore, the condensation problem on the CRCPs could be solved using the introduced method. The thermal comfort calculated according to temperature and humidity distributions demonstrated that the new system has the ability to maintain comfort conditions. Moreover, the calculated cooling load to preserve thermal comfort is much lower in the introduced method compared to the conventional system. The comparison of cooling load between the new configuration and the conventional system exhibited the energy saving potential up to 30% in the new system.

In this study, the asphaltene deposition and the fouling layer growth are modeled using the multi-fluid approach. The crude oil is considered as a multi-species fluid which the asphaltene species can deposit on the heat transfer surfaces due to the volume reaction. The effective mechanisms of asphaltene particle transport are the molecular and eddy diffusions. Therefore the species modeling approach is utilized for particles transport by diffusion processes in the carrier phase. To model the fouling layer growth without considering an initial thickness for the deposited layer, extra terms are added to the momentum equations of primary and secondary phases. The results of the numerical model are validated against available experimental data and a good agreement is seen. Finally, the developed model is applied for a specific case and the effect of fouling layer growth on the fluid velocity, the temperature variations, and the heat transfer rate are investigated. The results show that the heat transfer rate decreases during the fouling and the developed model could predict accurately the physics of fouling layer growth.

The aim of this research is to understand the mechanism(s) of RVR formation duringthe changes in operating condition from the Best Efficiency Point (BEP) to Part Load (PL). AComputational Fluid Dyn ...

Three-dimensional simulation of a multiphase flow is performed using the Eulerian-Eulerian finite volume method in order to evaluate the separation efficiency and velocity field of deoiling hydrocyclones. The solution is developed using a mass conservation-based algorithm (MCBA) with collocated grid arrangement. The mixture approach of the Reynolds stress model is also employed in order to capture features of turbulent multiphase swirling flow. The velocity field and separation efficiency of two different configurations of deoiling hydrocyclones are compared with available experimental data. The comparison shows that the separation efficiency can be predicted with high accuracy using computational fluid dynamics. The velocity fields are also in good agreement with available experimental velocity measurements. Special attention is drawn to swirl intensity in deoiling hydrocyclones and it is shown that the differences in velocity and volume fraction fields of different configurations are related to swirl distribution.

In this study, the effect of cone angle on the flow field and separation efficiency of deoiling hydrocyclones is investigated taking advantage of large eddy simulation. The dynamic Smagorinsky is employed to determine the residual stress tensor of the continuous phase. The method of Lagrangian particle tracking with an optimized search algorithm (closest cell) is applied to evaluate the separation efficiency of deoiling hydrocyclone. Simulations are performed on a 35-mm deoiling hydrocyclone with the three different cone angles of 6, 10 and 20 degree. The numerical results revealed that the changes in the cone angle would affect the velocity and pressure distribution inside hydrocyclone, and lead to changes in the separation efficiency. However, the large cone angle increases the tangential velocity and pressure gradient inside the hydrocyclone, but reduces the separation efficiency. The reasons behind the decrease in the separation efficiency are the flow structure and reduction of oil droplets residence time in hydrocyclones with large cone angles.

In order to evaluate the separation efficiency and flow field of deoiling hydrocyclones a three dimensional simulation is performed using large eddy simulation (LES) approach. Although this approach has been used in other types of hydrocyclones, the present work is a primer application of the LES approach for simulation of deoiling hydrocyclones. Due to anisotropic behavior of flow inside the hydrocyclones, LES is a suitable method to predict the flow field since it resolves large scales and models isotropic small scales. Obtained velocity field using the LES approach in comparison with other turbulence models is in good agreement with available experimental velocity measurements. The method of Lagrangian particle tracking with an optimized search algorithm (closest cell) is also used to evaluate the separation efficiency of deoiling hydrocyclones. Special attention is drawn to droplet drag coefficient, while the differences between separation efficiency curves using modified drag coefficient are also highlighted.

The boundary layer integral method is used to investigate the development of the turbulent swirling flow at the entrance region of a conical nozzle. The governing equations in the spherical coordinate system are simplified with the boundary layer assumptions and integrated through the boundary layer. The resulting sets of differential equations are then solved by the fourth-order Adams predictor-corrector method. The free vortex and uniform velocity profiles are applied for the tangential and axial velocities at the inlet region, respectively. Due to the lack of experimental data for swirling flows in converging nozzles, the developed model is validated against the numerical simulations. The results of numerical simulations demonstrate the capability of the analytical model in predicting boundary layer parameters such as the boundary layer growth, the shear rate, the boundary layer thickness, and the swirl intensity decay rate for different cone angles. The proposed method introduces a simple and robust procedure to investigate the boundary layer parameters inside the converging geometries.

This paper investigates the impact of the inflow conditions on simulations of a round jet discharging from a wall into a large space. The fluid dynamic characteristics of a round jet are studied numerically. A numerical method based on the control volume approach with collocated grid arrangement is employed. The \({k-\varepsilon}\) model is utilized to approximate turbulent stresses by considering six different inlet conditions. The velocity field is presented, and the rate of decay at the jet centerline is determined. The results showed that inflow conditions had a strong influence on the jet characteristics. This paper also investigates both sharp-edged and contoured nozzles. The effects of velocity, turbulence intensity, turbulence kinetic energy, and turbulence dissipation rate on flow field characteristics are examined. Results showed that the present simulations in both types of nozzles are in good agreement with experiments when considering the appropriate inflow conditions.

Three-dimensional simulation of incompressible flow in rotating tubes for both laminar and turbulent flows has been performed using a finite-volume method for elliptic flows. The influence of Reynolds number on the velocity field and the effects of temperature gradient on temperature profiles have been presented by numerical simulations. Also the effects of velocity field, flow regime, and temperature distribution along the tube have been studied from different points of view. The results have been calculated for rotational Reynolds numbers ranging from 1000 to 320,000. The comparisons between numerically calculated velocity field and the Nusselt number have shown satisfactory agreement with the experimental data.

In this research the fluid dynamics characteristics of a stellar turbulent jet flow is studied numerically and the results of three dimensional jet issued from a stellar nozzle are presented. A numerical method based on control volume approach with collocated grid arrangement is employed. The turbulent stresses are approximated using k–e and k–ω models with four different inlet conditions. The velocity field is presented and the rate of decay at jet centerline is noted. Special attention is drawn on the influence of corner angle and number of wings on mixing in stellar cross section jets. Stellar jets with three; four and five wings and 15–65° corner angles are studied. Also the effect of Reynolds number (based on hydraulic diameter) as well as the inflow conditions on the evolution of the stellar jet is studied. The Numerical results show that the jet entrains more with corner angle 65° and five wings number. The jet is close to a converged state for high Reynolds numbers. Also the influence of the inflow conditions on the jet characteristics is so strong.

This research presents numerical simulation of the unsteady flow field inside the draft tube of a Kaplan turbine at part load condition. Due to curvature of streamlines, the ordinary two-equations ...

In this research a comparison between k-epsilon and LES model for a deoiling hydrocyclone is conducted. Flow field of hydrocyclone is obtained by three-dimensional simulations with OpenFOAM code. Potential of prediction for both methods of this complex swirl flow is discussed. Large eddy simulation method results have more similarity to experiment and its results are presented in figures from different hydrocyclone cross sections., {"references":["A. Belaidi, M. T. Thew, S. J. Munaweera, \"Hydrocyclone performance\nwith complex oil-water emulsions in the feed\" in Can. J. Chem. Eng.,\nVol. 81, 2003, pp. 1159-1170.","C. Gomez, J. Caldenty, S. Wang, \"Oil/water separation in liquid/liquid\nhydrocyclons: part 1experimental investigation\", in SPE J., Vol. 7, 2002,\npp. 353-372.","R. G. Devorak, \"Separation of light dispersions in long hydrocyclones\",\nMaster of Science Thesis No. 1338609, Michigan State University,\n1989.","D. J. Simkin, R. B. Olney, \"Phase Separation and Mass Transfer in a\nLiquid-Liquid Cyclone\", in AIChE, Vol. 2, 1956, pp. 545-551.","Sheng H. P., Welker J. R., Sliepcevich C. M., \"Liquid-Liquid Separation\nin a Conventional Hydrocyclone\", in The Canadian J. of Chem. Eng.,\nVol. 52, 1974, pp.487-491.","D. A. Colman, \"The Hydrocyclone for Separating Light Dispersions\",\nPh.D. Thesis, Southampton University, UK, 1981.","D. Colman, M. Thew, D. Corney, \"hydrocyclones for Oil/Water\nSeparation\". in Int. Conf. on Hydrocyclones, BHRA, Cambridge, United\nKingdom, paper 11, 1980, pp. 143-165.","D. Colman, M. Thew, \"Hydrocyclone to Give a Highly Concentrated\nSample of a Lighter Dispersed Phase\". In Int. Conf. on Hydrocyclones,\nBHRA, Cambridge, United Kingdom, p 15, 1980, pp. 209-223.","D. Colman, M. Thew, \"Correlation of Separation Results From Light\nDispersion Hydrocyclones\", in Chem. Eng. Res. Des., Vol. 61, 1983, pp.\n233-240.\n[10] Z. Bai, H. Wang, S. Tu,\"Experimental study of flow patterns in deoiling\nhydrocyclon\", in Mineral Engineering, Vol. 22, 2009, pp. 319-323.\n[11] W. P. Jones, B. E. Launder, \"The Prediction of Laminarization with a\nTwo-Equation Model of Turbulence\", in International Journal of Heat\nand Mass Transfer, Vol. 15, 1972, pp. 301-314.\n[12] J. Smagorinsky, \"General circulation experiments with the primitive\nequations\", in Month. Weather, Rev. 91, 1963, pp. 99-165.\n[13] J. Deardorff, \"A numerical study of three-dimensional turbulent channel\nflow at large Reynolds numbers\", in Journal of Fluid Mechanics, Vol.\n41 (2), 1970, pp. 453-480.\n[14] P. Moin, J. Kim, \"Numerical investigation of turbulent channel flow\", in\nJ. Fluid Mech. Vol. 118, 1982, pp. 341-377.\n[15] W. Jones, M.Wille, \"Large eddy simulation of a jet in a cross flow\", in:\n10th Symposium On Turbulent Shear Flows, The Pennsylvania State\nUniversity, 1995, pp. 41-46.\n[16] M. Germano, U. Piomelli, P. Moin, W.H. Cabot, \"A dynamic subgridscale\neddy viscosity model\", in Phys. Fluids, 1991, pp. 31760-31765.\n[17] D.K. Lilly, \"A proposed modification of the Germano subgrid scale\nclosure method\", in Phys. Fluids A, Vol. 4, 1992, pp. 633-635."]}

In this research the fluid and thermal characteristics of a rectangular turbulent jet flow is studied numerically. The results of three dimensional jet issued from a rectangular nozzle are presented. A numerical method employing control volume approach with collocated grid arrangement was employed. Velocity and pressure fields are coupled with SIMPLEC algorithm. The turbulent stresses are approximated using k-epsiv model with two different inlet conditions. The velocity and temperature fields are presented and the rates of their decay at jet centerline are noted. The velocity vectors of a main flow and secondary flow are illustrated. Also effect of aspect ratio (AR) on mixing in rectangular cross section jets is considered. Investigated AR was among 1:1 to 1:4. The results showed that the jet entrains more with smaller AR. Special attention has been drawn on the influence of the Reynolds number (based on hydraulic diameter) as well as the inflow conditions on the evolution of the rectangular jet. An influence on the jet evolution is found for smaller Re, but the jet is close to a converged state for higher Reynolds numbers. The influence of the inflow conditions on the jet characteristics is so strong.