Problem 12.6. A fluid is constrained between two smooth surfaces a distanced apart in a gravitational field with a temperature gradient across the fluid. If a Bnard instability develops, show that it is possible to have square cells. Find the horizontal width of the cells in terms of

d. Find an expression for the velocity, v, of the fluid and sketch the flow in each cell. Assume that at the cell walls the fluid flows upward and has its maximum speed.