Particles suspending in complex fluids usually result in complicated flow behavior. It is vitally important to study the stress enhancements in the narrow region between two rigid particles. In this talk, we will show the pointwise upper bounds of the gradient and the second-order partial derivatives for the stationary Stokes/Navier-Stokes flow as the distance between two rigid particles approaches to zero in a bounded domain in dimension two and three. The optimality of these blow-up rates is demonstrated by establishing the corresponding lower bounds.