令球面上流函数为零 g+9*=0 v(a,0)=0→4x4a Q*=,Q 于是q=Q* 球外一点P的流函数表达式 oa r v(r,6)=-4汇 + coS β)4兀 (+cos a)+* ( , ) 0 0 * 4 4 Q Q l a a Q Q a l     =  − + =  = a Q a l q = Q = 2 *       = − + − + + + − a a r l Q a l Q Q a r         4 (1 cos ) 4 (1 cos ) 4 ( , ) 令球面上流函数为零， 于是 球外一点P的流函数表达式