How to make a realistic static cloud model in Unity?

I’m trying to make a single static cloud model in Unity. I can make a realistic one using Houdini VDB but It will be very coarse if I export it as a polygon mesh. Then I tried to use Unity particle system, link the particle shape to my poly mesh, but the cloud will be moving, instead of static. I’m pretty new to particle system. Any suggestions that can make it static? Thank you!