I am trying to simulate the blood flow in arteries by two way FSI (Fluent and Transient Structural). Every time I get the error of this sort:

"(DP 0) Element 191 located in Body "Solid" (and maybe other elements) has become highly distorted.  You may select the offending object and/or geometry via RMB on this warning in the Messages window.  Excessive distortion of elements is usually a symptom indicating the need for corrective action elsewhere.  Try incrementing the load more slowly (increase the number of substeps or decrease the time step size).  You may need to improve your mesh to obtain elements with better aspect ratios.  Also consider the behavior of materials, contact pairs, and/or constraint equations.  If this message appears in the first iteration of first substep, be sure to perform element shape checking. Named Selections for the offending element can be created via the Identify Element Violations property on the Solution Information Object."

I tried reducing the time step but it did'nt work. I am new to this field of FSI.  Any help to solve this issue would be appreciated.