Computation Domain and Grid Design

The computation domain is shown in Figure 12.15. It is designed primarily for the case U = 50.9 m/s and a boundary layer thickness 5 = 2 mm. In the cavity opening region, viscous effects are important. To capture these effects, a fine mesh is needed. Away from the cavity, the disturbances are mainly acoustic waves. By using the DRP scheme in the computation, only a very coarse mesh would be necessary in the acoustic region. The mesh design is dictated by these considerations. The computation domain is divided into a number of subdomains as shown in Fig­ure 12.15. The finest mesh with Ax = Ay = 0.0825 mm is used in the cavity opening region. The mesh size increases by a factor of 2 every time one crosses into the next subdomain. The mesh size in the outermost subdomain is thirty-two times larger than the finest mesh.


Figure 12.15. Computational domain showing the division into subdomains and their mesh size. D = 3.3 mm.