COMSOL 6.2 - Lift Force

Lift Force

Use the node to exert a lift force on particles in a fluid. Lift forces are applicable when particles move through a fluid in which the velocity field is nonuniform.

Supported formulations:

•

and

•

LIFT Force

Select a : (the default) or .


	Saffman and Wall induced lift forces are applicable for particles traveling through a creeping flow. The Saffman lift force is applicable for particles far from walls. The Wall induced lift force is a specialized formulation to account for the effects of nearby walls as particles move through pipes or channels.


	In 3D models, using the Wall induced lift force can cause a significant increase in computation time, due to the additional overhead of locating the nearest point on a wall for each particle at every time step. This is most noticeable if the boundary mesh is very fine.

Enter coordinates for the u (SI unit: m/s) based on space dimension. If another physics interface is present which computes the velocity field then this can be selected from the list.

The μ (SI unit: Pa·s) is taken . For enter another value or expression.

If is selected from the list it is only necessary to specify the set of domains in which the lift force is exerted. If is selected, the and selections are also shown. These two boundary selections are typically two parallel surfaces on either side of a parabolic flow profile.

Wall Corrections

This section is shown when is selected from the list. The settings are the same as for the Drag Force node.


	The lift force depends on the spatial derivatives of the fluid velocity components. When fluid velocity is computed by using any fluid flow interfaces such as Laminar Flow interface, the discretization of fluids should be P2+P1 or higher. For example in the Settings window of Laminar Flow interface, expand the Discretization section and choose P2+P1 or higher discretization from the Discretization of fluids list.


	Particle Motion in a Shear Flow in Theory for the Particle Tracing for Fluid Flow Interface.