Numerical Simulation of a Spanwise Vortex in a Periodic Forced Flow - Selected Topics of Computational and Experimental Fluid Mechanics - page 424

Fig. 4 Isovorticity surfaces of the spanwise vortex in a periodically forced flow at a t = 15 s

b t = 20 s and c t =

40 s

4 Time Convergence

Figure 5 shows the maximal Courant number (maximal over all the mesh) as a func-
tion of time for the cases studied here. Figure 5 a exhibits themaximal Courant number
in the pulsating flow. The curve never exceeds the value of 0.3, then the time conver-
gence is always guaranteed over all time integration. For the periodic forcing flow
( S

02) the curve has a maximal value of approximately 0.7 (see Fig. 5 b). Again,
the maximal Courant number is less than 1, that is, time convergence is guaranteed
for the periodic forcing flow.

= 0 .

(a) (b)

Fig. 5 Courant number in some of three coordinates. a The pulse case. b Theperiodicflowrate
case