(清华大学2006—2007学年春季学期期中考试试题)Giyen the steady,incompressible velocity distribution V=x+y)i+C(x+y)j+0k,where C is a constant,if conservation of mass is satisfied,find the value of C.Write down the strain rate tensor Sij=0.5(uij+uji)and the vorticity vector(▽×V).