Computational Fluid Dynamics Unit 1 CFD

Computacional fluid CFD

This report discusses the importance of Computational Fluid Dynamics and is there a need as compared to theoretical and experimental methods. The benefits of using CFD are detailed along with the limitations posed by using this method. Using the example of an idealised combustion chamber of an air turbine, modelling a physical process is explained. Important terms used in CFD including Discretisation, Numerical Grid, Initial and Boundary Conditions, and Turbulence modelling are discussed along with relevant applications where applicable.

Computational fluid dynamics (CFD) is a simulation tool, which uses powerful computer and applied mathematics to model fluid flow situations for the prediction of heat, mass and momentum transfer and optimal design in industrial processes.The sleek & beautiful aircraft roles down the run away, takes off & rapidly climbs out of sight within a minute, this same aircraft has accelerated to hypersonic speed; still within atmosphere. Its powerful supersonic engine continues to propel aircraft with velocity near 26000 ft/s orbital velocity and vehicle simply coasts into low earth orbit. The physical aspects of any fluid flow are governed by the fundamental principle as Newton's second law (Navier-Stokes equations).

Indian Journal of Public Health Research & Development, 2018

Ideal from the eighteenth century huge measure of research is going in the field of fluid flow and its application to regular problems. From the invention of the computer and development in the field of fluid mechanics, its governing equations and approach of numerical techniques, CFD has begun and has advanced to a great degree. The plan and the development procedure of any item finished the years has turned out to be moderately more simple and less tedious to the customary strategies, so here the fundamental intention of this paper is to give a history, have the significance and feasibility study of computational Fluid Dynamics (CFD) as a computational apparatus for different analysis of engineering related application based problems. It manages the present situation, generally extent of CFD, its pertinence for engineering problems, test for its validation of the obtained results and its focal points over the test strategies. CFD as an instrument can be connected for problems identified with turbo-machinery, building performance for various weather conditions, storm analysis, warm exchangers, completely created turbulent flow in pipes, analysis of fluid flow and airfoil of an airplane, cooling of electronic chips in the processor using constrained convection and so on.

This paper will answer a list of questions regarding the computational fluid dynamics (CFD). It will give a brief discussion regarding the significance of CFD and will recount the pros and cons of applying CFD. The following assignment will also give an overview of the terms that come under the ambit of CFD like discretization, numerical grid, initial conditions, boundary conditions, sweep, convergence, and turbulence modeling. The researchers such as Guang Xu et al. (2017), Raase and Nordström (2015), and Frigg et al. (2009) concluded that CFD is the science of the future as it cares in all aspects of life in the present and the future, CFD science treats the fluids mainly the air and the water as good and bad, bad when the CFD tries to find a way through the air and the water to get the minimum resistant for cost-effective and less fuel burning for greener, healthier and better world in many applications such submarines, air crafts, automobiles, ships, trains, motorbikes and too many other applications.

Computational Fluid Dynamics (CFD) is the emerging field of fluid mechanics in which fluid flow problems are solved and analyzed using computational methods and numerical algorithms. In fluid mechanics, there are generally three routes of work in the field, three ways to conduct experiments. The first category is theoretical, or analytical, fluid mechanics. Theoretical fluid mechanics includes theorizing, manipulating and solving equations with pen and paper. The Navier-Stokes equation governing incompressible fluid flow is an example of theoretical fluid mechanics. Secondly, many engineers and physicist work in the area of experimental fluid mechanics. Experimental fluid mechanics involves conducting actual physical experiments and studying the flow and the effect of various disturbances, shapes, and stimuli on the flow. Examples include waves generated by pools, air flow studies in actual wind tunnels, flow through physical pipes, etc. Lastly, a growing number of engineers, mathematicians, computer scientists, and physicists work in the area of computational fluid dynamics (CFD). In CFD, you may still run an experiment of waves across water, an airplane in a wind tunnel, or flow through pipes, but now it is done through the computer Instead of actual, physical, 3D objects. A computer model is created, and computer programmers code the equations representing the physical laws that govern the flow of the molecules of fluid. Then the flow results (such as velocity and pressure) are output into files that can be visualized through pictures or animation so that you see the result just as you do with physical experiments. In cases where an analytical, or theoretical, solution exists, CFD simulations and the mathematical models, which are coded in the computer program, are corroborated by comparison to the exact solutions. This comparative check is called validation. CFD is not yet to a point where solutions to problems are used without corroboration by existing, known, analytical or exact solutions when available. Validation is not to be confused with verification, however; validation is a check to make sure that the implemented, coded model accurately represents the conceptual, mathematical description and the solution intended to be modeled. Still, there are many times when there is no analytical solution. In these cases, one often uses a computational approach. In such cases without a known solution, CFD is used to www.intechopen.com

In this chapter, a general description of mathematical modeling using computational fluid dynamics (CFD) is presented. The numerical approximation to the conservation equations is presented in accordance with the form used by the commercial CFD code " PHOENICS. " The modifications required to adapt PHOENICS for the analysis of momentum and energy transfer in thermal sterilization are also presented. 4.1. INTRODUCTION TO COMPUTATIONAL FLUID DYNAMICS CFD is a numerical technique used for the solution of the equations governing fluid flow and heat transfer problems inside a defined flow geometry (Scott, 1994). CFD has wide applications in the areas of fluid and heat transfer within the aerospace and nuclear industries backed by the availability of powerful supercomputers. It has expanded into other industries such as the chemical and petrochemical industries. It is only in recent years that it has been applied to the food industry, with a limited variety of food-related problems being investigated (Scott and Richardson, 1997). CFD offers a powerful design and investigative tool to the process engineer in many applications. However, at present little use of this technology has been reported in the food industry. Its application in such areas would be beneficial for the better understanding of the complex interactions occurring in food systems. The development of CFD packages came from a need to solve complex fluid flow problems of a general nature for a wide range of geometry and boundary conditions (Hatton and Carpenter, 1976). CFD works by dividing the physical environment of interest into a two or three-dimensional (3-D) grid or mesh. It contains a number of discrete cells and can evaluate fluid velocities, temperature, and pressure inside every one of the cells where fluid flows. This is done by the simultaneous solution of the equations describing fluid flow, heat, and mass transfer. The use of CFD techniques to solve a fluid flow and heat transfer problem is split into three discrete parts: pre processing, processing, and post processing. In general, different computer programs that form the CFD code must undertake each of the three tasks. 4.1.1. Definition of a CFD Problem (Preprocessor) The first stage in solving a CFD problem is to define all the relevant parameters required by the CFD code prior to the numerical solution process, as follows: 33

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