Computational fluid dynamics packages

A commercial Computational Fluid Dynamics package (FIDAP Version 7.6, Fluid Dynamics International, Evanston, IL) based on the finite element method was used to solve the governing continuity, momentum and heat transport equations. A mesh was defined with more nodes near the wall and the entrance of the tubular heat exchanger to resolve the larger variations of temperature and velocities near the wall and the entrance. 

A numerical study of the effect of area ratio on the flow distribution in parallel flow manifolds used in a Hquid cooling module for electronic packaging demonstrate the useflilness of such a computational fluid dynamic code. The manifolds have rectangular headers and channels divided with thin baffles, as shown in Figure 12. Because the flow is laminar in small heat exchangers designed for electronic packaging or biochemical process, the inlet Reynolds numbers of 5, 50, and 250 were used for three different area ratio cases, ie, AR = 4, 8, and 16. 

With the widespread use of software packages to assist with computational fluid dynamics (CFD) of polymer flow situations, other types of viscosity relationships are also used. For example, the regression equation of Klien takes the form... 

Computational fluid dynamics (CFD) programs are more specialized, and most have been designed to solve sets of equations that are appropriate to specific industries. They can then include approximations and correlations for some features that would be difficult to solve for directly. Four major packages widely used are Fluent (http //www.fluent.com/), CFX (now part of ANSYS), Comsol Multiphysics (formerly FEMLAB) (http //www.comsol.com/), and ANSYS (http //www.ansys.com/). Of these, Comsol Multiphysics is particularly useful because it has a convenient graphical-user interface, permits easy mesh generation and refinement (including adaptive mesh refinement), allows the user to add phenomena and equations easily, permits solution by continuation methods (thus enhancing... 

The use of computer generated solutions to problems and computational fluid dynamics is also another approach of comparing impellers and process results. There are software packages available. It is very helpful to have data obtained from a laser velocity meter on the fluid mechanics of the impeller flow and other characteristics to put in the boundary conditions for these computer programs. 

Software In view of the rigor involved in numerical solution, many commercial software packages have been developed that serve the purpose of computational fluid dynamics (CFD). Appendix 2. A gives a listing of sources for various commercial as well as free CFD codes. These CFD codes may be broadly categorized into either finite volume method based or finite element method based. For a detailed account of computational methods, see the books by Patankar (1980), Ferziger and Peric (2002), Ranade (2002), Chen (2005), Reddy (2005), and so forth. 

Considerable advances have been made in recent years, using computational fluid dynamics (CFD), towards a better understanding of mixing effects and their influence on precipitation processes (Leeuwen, Bruinsma and van Ros-malen, 1996 Wei and Garside, 1997 Leeuwen, 1998 Al-Rashed and Jones, 1999 Zauner and Jones, 2000b). Several commercial and private CFD packages are now available to facilitate solution of the relevant mass, momen-... 

Omran et al. have proposed a 3D, single phase steady-state model of a liquid feed DMFC [181]. Their model is implemented into the commercial computational fluid dynamics (CFD) software package FLUENT . The continuity, momentum, and species conservation equations are coupled with mathematical descriptions of the electrochemical kinetics in the anode and cathode channel and MEA. For electrochemical kinetics, the Tafel equation is used at both the anode and cathode sides. Results are validated against DMFC experimental data with reasonable agreement and used to explore the effects of cell temperature, channel depth, and channel width on polarization curve, power density and crossover rate. The results show that the power density peak and crossover increase as the operational temperature increases. It is also shown that the increasing of the channel width improves the cell performance at a methanol concentration below 1 M. 

This is commonly done by a stroboscopic measurement setup comprising a microscope-mounted CCD camera with a short exposure time and a flashlight which are synchronized to the rotational motion (Fig. 15). Regarding simulation, the majority of commercially available computational fluid dynamic (CFD) packages is able to cope with rotating channels. 

Computational fluid dynamics (CFD) based on the continuum Navier-Stokes equations Eq. 2 has long been successfully used in fundamental research and engineering design in different fluid related areas. Namrally, it becomes the first choice for the simulation of microfluidic phenomena in Lab-on-a-Chip devices and is still the most popular simulation model to date. Due to the nonlinearity arising from the convention term, Eq. 2 must be solved numerically by different discretization schemes, such as finite element method, finite difference method, finite volume method, or boundary element method. Besides, there are a variety of commercially available CFD packages that can be less or more adapted to model microfluidic processes (e.g., COMSOL (http //www.femlab.com), CFD-ACE+ (http // www.cfdrc.com), Coventor (http //www. coventor.com), Fluent (http //www.fluent.com), and Ansys CFX (http //www.ansys.com). For majority of the microfluidic flows, Re number is... 

As previously mentioned, the analysis of microfluidic systems can be rather difficult for a variety of reasons. The direct implementation of the Navier-Stokes equations toward surface-directed microfluidic systems requires careful attention when considering the advection of the free surface and the associated curvature of this surface. Consequently, sophisticated computational fluid dynamics software packages are required for a comprehensive three-dimensional analysis of the fluid transport within surface-directed microfluidic devices. However, a time-consuming comprehensive analysis may be beyond the requirements of designing and manufacturing functional surface-directed microfluidic platforms. Consequently, empirical approximations and scaling arguments are commonly used in the characterization of microfluidic physics. 

The solution to the model of the flow interaction with a fibrous assembly requires application of numerical methods collectively known as computational fluid dynamics (CFD) implemented in computer software packages which use finite-element methods. 

Computational Fluid Dynamics (CFD) and Process Simulation are important tools for the design and optimization of chemical processes (Bezzo et al., 2000). CFD is a particularly powerful tool for the study of fluid dynamics and heat transfer with detailed account of complex equipment geometry. Nonetheless, despite many recent improvements, CFD s ability to describe the physics or solve the underlying numerical problems in several application areas is still limited. Adsorption technology is an application area where the numerical methods employed in most CFD packages are inadequate to solve the strongly coupled nonlinearities introduced by the presence of the adsorbed phase. 

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