MPCD concentric cylinders geometry

[mphoward]

Description

A bounce-back geometry for particles confined between two cylinders, where the outer cylinder can be rotated with respect to the inner cylinder, would be helpful for simulating shear flow. This is called a Taylor–Couette geometry, and it is used a lot in CFD and experiments.

Proposed solution

A new geometry class will be added to hoomd.mpcd.geometry called ConcentricCylinders. On the backend, it will use mostly autogenerated code once the C++ geometry is created.

Additional context

@jinnyjc is working on this.