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What is CFD?
  Computational Fluid Dynamics (CFD) is a branch of engineering that deals with the numerical solution of the equations governing the conservation of mass, momentum, energy, and related parameters. The numerical solution is obtained over a finite number of locations (called grid points) in the calculation domain. A discretization method is used to convert the parent differential equation into algebraic relations involving the values of the dependent variables for a group of grid points. A suitable algorithm is used for the solution of these algebraic equations. Some examples of the commonly used discretization methods are the finite-difference method, finite-volume method, and finite-element method. Here, we give a brief overview of the finite-volume method, which is the basis of SOLVENT; for other methods, please refer to appropriate textbooks.
  Finite-Volume Method
  In the finite-volume (or control-volume) method, the calculation domain is divided into a number of nonoverlapping control volumes such that there is one control volume surrounding a grid point. The differential equation is integrated over each control volume. Piecewise profiles expressing the variation of the dependent variable between two grid points are used to evaluate the required integrals. The result is the algebraic equation containing the values of the dependent variables for a group of grid points. The most attractive feature of the finite-volume method is that the resulting solution would imply integral conservation of quantities such as mass, momentum, and energy is exactly satisfied over any group of finite volumes and, thus, over the entire calculation domain. This property exists for any number of grid points-not just when the number of grid points becomes large.
  Steps in a CFD Simulation

In broad terms, CFD simulation of a physical situation involves the following steps:

  1. Specification of the geometric details.
  2. Specification of the equations to be solved (i.e., the mathematical model). In addition to the basic equations governing the conservation of mass, momentum, and energy, these equations will include, for example, the equations for turbulence model, combustion model, and radiation model.
  3. Specification of the boundary and initial conditions.
  4. Specification of the transport properties.
  5. Use of a numerical method for solving the equations. Often special techniques must be employed to resolving the coupling between various equations (e.g., the velocity-pressure coupling); these details are part of the numerical method.
  6. Post-processing of the numerical results.
  Advantages of CFD
  Use of a CFD model allows you to analyze your problem in much greater detail, in much shorter time, and at a much lower cost compared to testing. A CFD model provides complete details of your problems. For example, you obtain the values of pressure, velocity components, temperature, etc., over the entire calculation domain. CFD gives you the ability to simulate realistic conditions. You no longer have to resort to small-scale or cold-flow models. CFD is an ideal complement to traditional testing and experimentation. It gives you an insight into the physical processes and enables you to improve your design.