The drag laws that are suitable for dense gas-solid flow are:

A detailed theoretical background to the correlations, along with a recommendation of when to use each model, can be found in Fluid-Solid Exchange Coefficient (see also Specifying the Drag Function in the User's Guide). All these correlations incorporate group effects and, therefore, are dependent on the particle phase volume fraction. Thus, the drag models are only available when the DPM volume fraction is computed, that is, in conjunction with the Dense Discrete Phase Model.