Computation And Error Estimation Of Different Models For Two Phase Flow Containing Fine Particles

The size of fine particles range from10-8m to10-3m, including suspended particles inthe air, dust, fine sediment, etc. The fine particles are harmful to human health, damage theecological environment and cause great loss to industrial production. These hazards arecaused by the fine particles flowing with fluid, as a result, the two phase flow containingfine particles becomes to be a hot research topic. Research about how to solve the controlequations of two phase flow containing fine particle simply and rapidly has very importantmeaning.Saffman model of two phase flow are very common in the present. For two phase flowis concerned, if the ratio of particles’ and fluid’s density is very large and the particles massconcentration is small enough (meeting the dilute phase conditions), Saffman model can beapplicated very well. In Saffman theory, the presence of coarse particles in fluid increaseflow stability and the presence of fine particles in fluid reduce flow stability. In the case ofSt1, particles’ size is considered to be fine, particles can be seen as move with fluid andvelocity distributions of particles and fluid are deemed to be identical. Based on thecharacteristics of small particles, according to the Saffman model of two phase flow, thesimplified model of two phase flow containing fine particles can be deduced. Thesimplified model are controlled only by fluid phase. Through the simplifition, we canreduce the number of equations and unknowns and reduce the difficulty to solve thenumerical calculation of two phase flow containing fine particles.The auther choose the Euler-Euler’s method as the numerical simulation method tosolve two phase flow models and choose a driven square cavity as the flow field. Thesquare cavity is divided into90*90uniform grids and time step length is defined as t=10-3,meeting the stability conditions.The auther uses matlab programming to solve the numerical calculation of the Saffmanmodel and the simplified model of two phase flow containing fine particles. By analyzingsolved fluid phase velocity u, v through both model at stable time,the auther displays thechange rules of the average relative error in the flow field of u, v with the flow parameters such as St, Re, and f. The results show that in the case of St1, particle phase move withfluid, the relative error of particle and fluid velocity is small, meet simplified premisecondition; If St number is small, Re number is low and particle mass concentration f issmall enough, the simplified model can replace Saffman model of two phase flowcontaining fine particles reasonably.