Ansys Employee

Cell quality looks OK. How well resolved is the mesh?  When complex models fail it's best to turn things off until it works. Then look at the flow field to check for areas that may be causing problems with the more complex set up. Resolve these and continue turning physics on. 

As a beginner I recommend getting some practice with something other than a 3 phase bioreactor - they're not simple models. 

What volume fraction of sand are you patching into the domain?