Hello Rohan,

Add a solid body inside the container to represent the fluid. Use shared topology so the fluid is connected to the container. Assign a fluid material to the body. Mesh the fluid body. What element shape was created?  If Quadratic Tet elements, assign FLUID221 elements to that body. If Linear Hex elements, assign FLUID30 elements to that body. Solve the model using Modal Acoustics. Does the fluid completely fill the container or is there a free surface?

A point mass with no MMI causes the node to have only 3 translational DOF while a point mass with MMI causes the node to have an additional 3 rotational DOF.