How to choose a configuration for simulation (ANSYS, CFD)?

Question

GPGPU

Hello.
I ask for advice on organizing a workstation for modeling tasks: at work they said to configure a computer, powerful, for solving problems in ANSYS CFD / CFX and the like. Tasks - computational fluid dynamics. Large grids, solving partial differential equations using the finite volume method, using dynamic grids in 3D problems, etc.
Budget - up to 500,000 rubles. More - just very targeted.
There are two options:
1. On the chart: Tesla K20, Tesla K40.
2. Cluster. What I know is that a good interconnect is needed, in this case it will be InfiniBand, but I don’t really understand modern blades and other server equipment. That is, I’ll figure it out, of course, but I won’t be able to do everything right away, that’s why I’m asking for advice.
Please tell me where to start, ready to answer clarifying questions.
Thank you.