ABSTRACT
Another example concerns where both the fluid and solid phases are regarded as continua. Chen and Wood (134). The mean velocities of both phases are taken as equal although a local velocity difference is assumed in order to calculate particle forces by velocity difference and response time. The time averaged equations are formed and hence further assumptions of the flow field must be introduced in order to generate sufficient equations for a solution to be obtained. This is the so called 'closure' requirement and is brought about by the loss of information caused by the time averaging of the differential equations. Time averaging is introduced in order to reduce the computational work to practical proportions. The flow field is characterised by the k-E model, where k represents the kinetic energy of the turbulent velocity fluctuations and E is a measure of its dissipation rate. In this model the diffusivity is allowed to vary and is computed from a product of the turbulence length and velocity scales. The details of the model are those proposed by Jones and Launder (135).
