Loads are part of the boundary conditions you define for the simulation. There are various load types available to apply:
Faces, edges, and vertices.
When selecting more than one input, all inputs must be the same entity type.
Apply a force of the specified magnitude to the selected faces, edges, or vertices.
By default, Force is applied:
Flip reverses force direction.
Apply a pressure of the specified magnitude to the selected faces.
Face or Edge
Apply gravity of the specified magnitude normal to the selected face or parallel with the selected edge.
Flip reverses gravity direction.
Apply a load: