FLOW AROUND A CYLINDER - istiarto

– 5.47 –
Fig. 5.24 Surface boundary computation: (a) present approach, (b) proposed
modification, and (c) 2D mesh of the surface boundary.
Referring to Fig. 5.24b, the proposed approach works as follows:
� Impose zero pressure at the surface, pt = 0, and obtain the pressure at the cell center
by assuming a hydrostatic distribution: pP � pt � �gz�z t � zP�. � Interchange pc and qt in the pressure-correction equation for cells neighboring the
surface; at those cells, the pressure-correction equation (see Eq. 4.68) reads:
p c
qt � a nbpnb
� b p where the source term bp does not contain qt any more.
�
nb
� Obtain the surface velocity based on the computed discharge: V t � q t S t , whose
components are u
�� t � V t � ��
e t,x and v
�� t � Vt � ��
e t,y.
� Solve Eq. 5.6, at the end of each time step or after the p c has reduced to sufficiently
small numbers, to get the surface position, � t .