Computational Fluid Dynamics (CFD) is the application of computational techniques to the solution of complex fluid dynamic problems. For example, if external energy, such as heat, is applied to the four sides of a rectangular or square metal plate, what is the temperature at each point of the plate's central region at the time the heat is applied and a few seconds later? The use of CFD techniques will solve this issue. Again, if you want to know the fluid velocity inside a rectangular flume that is half full of water and has pressure applied to it on all sides, you can solve the fluid dynamic equations by using a variety of computation techniques to come up with the answer.