The driven cavity problem is considered. The driving force is not constant, but may be a complicated pattern across the top of the cavity. The problem is motivated by certain geophysical flows, such as circulation within lakes and how they are affected by atmospheric forcing at the surface. The results are obtained computationally using the lattice Boltzmann method employed on a two dimensional hexagonal lattice. Reynolds numbers range to 3000. An antisymmetric sinusoidal velocity pattern is used to simulate the nonconstant forcing. The simulations include an initial disturbance, developed with unidirectional forcing. Results exhibit a steady symmetric, steady asymmetric or unsteady asymmetric pattern, depending on the size of initial disturbance and Reynolds number.
