Use the Lift Force feature to exert a lift force on the particles. Two formulations of the lift force are available. Both expressions for the lift force are valid when the angular velocity of the particle can be neglected and a no-slip boundary condition applies at the particle surface.
The following sections describe the available lift force models. Each of these models can be used by selecting the appropriate option from the Lift law list in the settings window for the
Lift Force node. Use the
Saffman lift force when particles are in a nonuniform velocity field far from walls. The
Wall induced lift force applies to particles close to the walls of a flow channel.
The Saffman lift force
FL (SI unit: N), described in
Ref. 13, is given by
The Saffman lift force is only nonzero for particles that have not yet been entrained in the surrounding fluid. Once a particle has reached equilibrium with the surrounding fluid velocity, the Saffman lift force is zero. To model the inertial lift force on particles in a flow channel, which is typically nonzero even after the particles become entrained in the flow, consider using the
Wall induced lift force described in the following section.
The Wall induced lift force model described in
Ref. 14 uses a first order correction to the velocity profile at the channel walls and a second order correction at the surface of the particle in order to account for higher-order derivatives of the fluid velocity, compared to the
Saffman model. It is given by