Devendra Badgujar
Forum Moderator

Hello Matthew, 

It looks like you have included all the bodies in Simulations and some of them seem to be overlapping on each other. Try exluding the bodies from simulation which you do not want. 

If you see the SID at the bottom centre it shows Conjuagte heat transfer study and not fluids simualtion. Keep only external fluids domain and exclude other bodies to perform external flow simualtion over the disk. 

Please go through this courses on Fluid Flow Simulation in Ansys Discovery | Ansys Courses & CHT Analysis in Ansys Discovery | Ansys Courses

for better understanding on how to perform simulations in Ansys Disocvery.