CFD Process
CFD attempts to use computers to solve the equations of motion numerically. As is the case in any mechanical problem, the equations of motion of fluid flows are based more or less on Newton’s laws of motion. These equations are written in a mathematical form and solved using a computer. The computer divides the fluid and solid volumes into a “mesh” and predicts the flow characteristics (ie velocity, pressure, temperature etc) at each mesh element (ie at a particular point) and then moves on to the next point/mesh volume, thereby building a picture of the full flow.
However, the prediction of a particular (unique) flow requires more than just a description of the equations of motion. A good prediction requires:
- The geometry that bounds the flow ie CAD or a numerical description of the geometry
- The equations of motion relevant to the flow problem
- Material properties of the fluids and solids involved
- The conditions at the boundaries to the problem domain (boundary conditions)
Thus you have to provide a large amount of information in order to develop a good flow prediction even before getting into the intricacies of using the CFD software.
The software is used to perform four basic tasks:
- Import the CAD geometry and mesh the fluid and solid domains/zones
- Set up the equations of motion, material properties and boundary conditions
- Solve for the case for the fluid/solid properties
- View and analyse the computed solutions
The CAD geometry is therefore the essential starting point for the CFD process.
