cylinder flow

There are Two cases.In the first case the solution converges and gives an accurate result. However in the second case, the solutions diverge.
case 1: The circle and rectangle are attached. Only the circle has fixed displacement boundary condition.In this condition,For both flexible and rigid plate the problem converges.
case 2: The whole circle as well as the left edge of the rectangle have a fixed displacement boundary condition. In this case, for both rigid or flexible assumptions of the rectangular plate, the solutions diverge. How can I sort out this issue?