FLOW AROUND A CYLINDER - istiarto

4.5.3 Outflow boundary
– 4.32 –
Suppose that the outflow lies at the east face of the boundary cell P (see Fig. 4.7). Across
the outflow face, the convective flux is computed according to the upwinding principle of
Eq. 4.28:
C � ��1 � ��1
�F � � q
�� e e �P � qout �P
while the diffusion flux is set to zero:
F D � � � 0
e
leading to a simplified form of Eq. 4.43:
��
F � ��1
e � qout �P
�
where
��
qout is either imposed or computed from the upwinding of P value at the former
iteration step:
��
q �
�
out � Vout
�
�Se � VP � Se
The same upwinding process finds the other variables at the boundary node E.
� E � � e � � P
Momentum and k-� equations
Fig. 4.7 Outflow boundary.
� set all coefficients related to node E in Eq. 4.52 to zero:
C D C D
aE � aE � a P
� � ��a E P�
� b
E D � � � b
E 1D � � � b
E 2D � � � 0
E