A liquid of density p and viscosity flows down an open channel of width W on

A liquid of density p and viscosity μ flows down an open channel of width W on a channel slope sin θ. The mean speed V is believed to depend on, among other things, the depth (d), the gravitational acceleration (g), and the roughness height (ε). Find the dimensionless parameters that may affect the coefficient k in the formula V = k √dg sin θ.