Gas-solid flows are encountered in many industrial applications such as fluidized beds and coal gasification. The design and scale-up of such industrial devices required a better understanding of the characteristics of gas-solid suspensions. Device-scale computational fluid dynamics (CFD) simulations that solve for average quantities such as solid volume fraction and phasic mean velocity fields are being extensively used in the industrial design process. The capability of the simulations to accurately predict the characteristics of gas-solid flow depends upon the accuracy of the models for unclosed terms that appear in the equations for mass, momentum and energy conservation. Hrenya and Sinclair (1997) show that the particle granular temperature (particle velocity variance) plays an important role in the prediction of the core annular structure in riser flows. In statistically homogeneous suspensions undergoing elastic collisions, the particle acceleration-velocity covariance alone governs the evolution of granular temperature.