Introduction to CFD

From CFD-Wiki

What is CFD?

Fluid dynamics is a field of science which studies the physical laws governing the flow of fluids under various conditions. Great effort has gone into understanding the governing laws and the nature of fluids themselves, resulting in a complex yet theoretically strong field of research.

Computational Fluid Dynamics or CFD as it is popularly known, is used to generate flow simulations with the help of computers. CFD involves the solution of the governing laws of fluid dynamics numerically. The complex set of partial differential equations are solved on in geometrical domain divided into small volumes, commonly known as a mesh (or grid).

CFD has enabled us to understand the world in new ways. We can now see what it is like to be in a furnace, model how blood flows through our arteries and veins and even create virtual worlds. CFD enables analysts to simulate and understand fluid flows without the help of instruments for measuring various flow variables at desired locations.

Where CFD scores

There are various reasons why CFD is becoming popular, some of which are:

• CFD allows numerical simulation of fluid flows, results for which are available for study even after the analysis is over. This is a big advantage over, say, wind tunnel testing where analysts have a shorter duration to perform flow measurements.
• CFD allows observation of flow properties without disturbing the flow itself, which is not always possible with conventional measuring instruments.
• CFD allows observation of flow properties at locations which may not be accessible to (or harmful for) measuring instruments. For example, inside a combustion chamber, or between turbine blades.
• CFD can be used as a qualitative tool for discarding (or narrowing down the choices between), various designs. Designers and analysts can study prototypes numerically, and then test by experimentation only those which show promise.

What CFD is not

• CFD is not yet at the level where it can be blindly used by designers or analysts without a working knowledge of numerics involved.
• Despite the increasing speed of computation available, CFD has not yet matured to a level where it can be used for real time computation. Numerical analyses require significant time to be set up and performed.
• CFD is still an aid to other analysis and experimental tools like wind tunnel testing, and is used in conjunction with them.