1. An Introduction to Computational Fluids Dynamics Prapared by: Chudasama Gulambhai H (130920105006) Azhar Damani (130920105007) Dave Aman (130920105008) Dadia Ankur (1309201050010) Veerayatan group of Institute, FOE& FOM- Mandvi

2. n the analysis of systems involving fluid flow, heat transfer, chemical reactions, by means of computer based simulation n 17th century the “hydraulicists” n 18th and 19th - the “mathematicians” n 1960 - two fold approach – theory and experiments n Now we have CFD as a tool that complements theory and experiments (it will never replace these!) n CFD is both a research tool and design tool What is CFD?

3. n CFD has lagged behind developments in stress analysis codes n Powerful computers now make CFD more accessible n Advantages of CFD over experiments u reduction in lead time and costs of new designs u ability to study systems where controlled experiments are difficult to perform (large systems) u ability to study systems under hazardous conditions at and beyond normal performance limits u detail of results What is CFD?

4. n Aerospace n Automobile and Engine Applications n Appliances n Boats n Computers Applications

5. n CFD codes are structured around the numerical algorithms that can tackle fluid flow problems n Three main elements: 1.Pre Processor 2.Solver 3.Post Processor How Does a CFD Code Work?

6. n Consists of the input of a flow problem to CFD n User Activities: u define geometry & generate grid (50% time) u selection of phenomena to be modeled u definition of fluid properties u specification of boundary and initial conditions 1) Pre-Processor

7. Three primary numerical solution techniques  finite difference, finite element, finite control volume The numerical method performs the following:  Approximates the unknown variables by simple functions  Discretization by substitution of the approx-imations into the governing flow equations and subsequent mathematical manipulations  Solution of the algebraic equations 2) Solver

8. Finite difference methods describe the unknowns  of the flow problems by means of point samples at the node points of a grid co-ordinate lines Solver - Finite Difference Method Truncated Taylor series expan- sions are used to generate finite difference approximations of the derivatives of  in terms of point samples of  at each grid point and its immediate neighbors

9. u Based on control volume formulation of analytical fluids u The domain is divided into a number of control volumes (aka cells, elements) - the variable of interest is located at the centroid of the control volume. u The differential form of the governing equations are integrated over each control volume. u Finite difference approximations are substituted for the terms in the integrated equations (discretization)  converts the integral equations into a system of algebraic equations. u Set of algebraic equations are solved by an iterative method. Solver - Finite Volume Method

10. n Provides a “user friendly” (??) way to look at the results of a simulation u Domain geometry and grid display u Vector Plots u Contour Plots u Particle Tracking 3) Post Processor

11. n Results of CFD are at best as good as the physics embedded in it as at worst as good a its operator n THESE PROBLEMS ARE COMPLEX n Prior to running a simulation there is a stage of identification and formulation of the flow problem in terms of the physical and chemical phenomena that need to be considered. n A successful simulation has u converged solution u grid independence Problem Solving With CFD