Factors Determining the Strength of Secondary Flow

An analytical equation which includes a secondary velocity is used to identify directly the various factors influencing the nature and strength of secondary currents in straight channels. A major part of the evaluation is based on data obtained in calculating secondary velocities. A family of isovels of the primary flow and the orthogonal trajectories of this family are used as a coordinate system. In such a coordinate system the shearing force, the shear gradient, and the gradient of the combined force of pressure and gravity, (which appear in the equation of motion in the direction of the primary flow) maintain the secondary flow in the direction perpendicular to isovels of the primary flow. The gradient of the primary flow velocity is also an important factor determining the strength of secondary flow.