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Droplet evaporation is a typical multiphase flow with various applications in many natural phenomena and industrial processes. Different numerical methods have been used to simulate this type of flow. Front-Tracking is one of the common methods in the study and simulation of multiphase flows. The Front-Tracking method requires very fine resolution when dealing with high density ratios with phase change. As a result, Front-Tracking method has rarely been used for solving problems at high-density ratios. In this paper, by using a two-step algorithm for moving the front, the Front-Tracking method is modified for problems with high-density ratios. Also, the fluid around the droplet is considered as a gas mixture, and the generated vapor is considered as a different component from the primary gas that surrounds the droplet. The results of the two-step algorithm are compared with the existing algorithm, and the available analytical results for a static droplet. The evaporation of a falling droplet is also studied, and the results of the two-step algorithm and common algorithm are compared. The effect of droplet deformation on the evaporation process for a falling is investigated. The effect of vapor properties on evaporation rate is also studied. The two-step algorithm is used for different three-dimensional cases, and static droplet evaporation is simulated. Results are compared with existing analytical results. Next, a falling droplet is modeled and the results are compared with experimental data. The effect of density ratio on falling droplet evaporation is also investigated. Finally, two and three-dimensional results are presented and compared for a specified case. For some cases, the conservation of mass and the dependence of results to grid resolution are presented which indicates the accuracy of the numerical method. [ABSTRACT FROM AUTHOR]

This paper presents a combined stabilized mixed finite element and discontinuous Galerkin method for coupled Stokes-Darcy flows model with transport, where the fluid viscosity depends on the concentration. We use nonconforming piecewise linear Crouzeix-Raviart (C-R) element to approximate velocity, piecewise constant function to approximate pressure and the symmetric interior penalty Galerkin (SIPG) method to solve concentration equation. A "cut-off" operator is introduced into SIPG scheme to avoid the assumption on the boundness of infinity norms of approximate velocity in convergence analysis. Optimal a priori error estimates for the full discrete scheme are obtained. Finally, some numerical examples are presented to verify the theoretical analysis, and a water injection oil production process is simulated to illustrate the practicability of our method. [ABSTRACT FROM AUTHOR]

Modelling the thermodynamic and hydrodynamic interactions of suspended particles is a significant and ongoing numerical challenge. Addressing this is necessary in order to be able to fully model numerous industrial and scientific processes of practical interest. This paper describes extensions to a local and a non-local technique for the calculation of transient conjugate heat transfer within a lattice Boltzmann framework. The interface transition between phases in both methods has been incorporated via a partially saturated boundary condition that weights material properties and allows straight and curved boundaries to be captured. Transient and steady-state performance of the two methods has been compared using a number of static and dynamic problems to evaluate their suitability for modelling particle suspensions. In a number of the static tests the non-local method produced better results however for the dynamic cases the local method demonstrated more accurate behaviour. [ABSTRACT FROM AUTHOR]

A challenge in the additive manufacturing process of laser beam melting of metals is the formation of residual stresses, which can cause large part deformations, when the part is released, lower the application range concerning tensile loads and provoke cracks. Due to the complexity and the interaction of different process parameters, the use of experimental studies for investigation is tedious and costly. An effective approach to analyze the effects is the numerical process simulation based on the method of finite elements. In this paper, the recently developed method of Mechanical Layer Equivalent for fast calculations of process induced distortions in laser beam melting is used to analyze the residual stresses during laser beam melting. For this purpose, small test samples have been generated additively and residual stresses have been measured by X-ray diffraction and compared to simulated values. The results show that despite the simplifications the model inhibits reliable prediction of residual stresses can be achieved. [ABSTRACT FROM AUTHOR]

Abstract: Cardenas-Barron [L.E. Cardenas-Barron, Economic production quantity with rework process at a single-stage manufacturing system with planned backorders, Computers and Industrial Engineering 57 (2009) 1105–1113] minimizes the annual total relevant cost to find the economic production quantity with rework process at a manufacturing system and assumes that is convex. So, the solution satisfying the first-order-derivative condition for will be the optimal solution. However, this paper indicates that does not necessarily exist although is convex. Consequently, the main purpose of this paper is two-fold: [(A)] This paper tries to develop the sufficient and necessary condition for the existence of the solution satisfying the-first-derivative condition of . [(B)] This paper tries to present a concrete solution procedure to find the optimal solution of . [Copyright &y& Elsevier]

Abstract: The objective of this paper is to perform the optimal design of a novel press system with Stephenson-I mechanism for deep drawing, and validate its feasibility. First, the system is presented and its advantages are discussed. Then, kinematic analysis is conducted by using the vector loop method. Moreover, the kinematic dimensions of the variable coupling are synthesized by using an optimization method. Furthermore, the proposed approach is illustrated by a design example. Finally, the solid model of the proposed design is established, and then kinematic simulation is performed by employing ADAMS software. The results show that proposed new press system is feasible and of better output motion for deep drawing. In addition, it has the advantages of easy manufacture, lower cost, higher precision, and easy adjustability. [Copyright &y& Elsevier]

Abstract: Supply chain management is concerned with the coordination of different parts of the production system. Companies have realized that they must closely collaborate with the suppliers of their strategic components or products. Recently, developing integrated inventory models for the supplier selection problem has attracted a significant amount of attention amongst researchers. In these models some incentives are required from the vendors to motivate the buyer to change his (her) policies to the policy which is optimal for the entire system. Quantity discount policies are used as common incentives in the literature. However, the literature on this problem does not incorporate quantity discount into the coordination model. This paper develops a multi-objective mixed integer nonlinear programming model to coordinate the system of a single buyer and multiple vendors under an all-unit quantity discount policy for the vendors. Due to the complexity of the problem two well known meta-heuristic algorithms are proposed to solve the problem. An illustrative example is given to show the behavior of the model. Results obtained from solving the sample problems show good performance of the proposed algorithms in finding the optimal solutions. [Copyright &y& Elsevier]

Abstract: This study employs mathematical modeling along with a recursive searching algorithm to determine the optimal run time for an imperfect finite production rate model with scrap, rework, and stochastic machine breakdown. In real-life manufacturing systems, generation of defective items and machine breakdown are inevitable. The objective of this paper is to address these issues and to be able to derive the optimal production run time. It is assumed that the proposed manufacturing system produces defective items randomly, a portion of them is considered to be scrap, and the other portion can be repaired through rework. Further, the proposed system is subject to random breakdown and when it occurs, the abort/resume (AR) policy is adopted. Under such an inventory control policy, the production of the interrupted lot will be resumed immediately when machine is fixed and restored. Mathematical modeling along with a recursive searching algorithm is used for deriving the replenishment policy for such a realistic production system. [Copyright &y& Elsevier]

The numerical investigation of the interaction of large, solid particles with fluids is an important area of research for many manufacturing processes. Such studies frequently lead to models that are very large and require the use of parallel solution techniques. This paper presents the results of a parallel implementation of a serial code for the direct numerical simulation of solid-liquid flows. The base code is a serial, arbitrary Lagrangian-Eulerian (ALE) formulation of the equations of motion, which views that particles as solid bodies are embedded into the flow domain. This particular model poses some interesting difficulties for domain decomposition type approaches for parallel solutions. In particular, it is not fully understood how the partitioning of the particles among the subdomains influences the performance of parallel solvers. We present several strategies for the partitioning of the solid particles, focusing on the effectiveness of these techniques in terms of parallel speedup and efficiency. [Copyright &y& Elsevier]