On the numerical oscillations in the simulation of circulating fluidized bed reactors using the finite volume method with collocated grids

Circulating fluidized bed (CFB) reactors are employed in many industrial processes such as catalytic cracking, combustion and residue incineration. Numerical tools are necessary for the development and optimization of CFB reactors. For single-phase flows the numerical techniques are well developed However, for the two-phase flow present in CFB reactors, some numerical problems can appear. This work shows that when the mass flaw of the particle phase through the control volume planes is obtained from linear interpolation of the particle phase velocities using the finite volume method with collocated grid, numerical oscillations are present in the solution. This work also shows that these numerical oscillations can be eliminated by calculation of mass now through the control volumes planes by interpolation of the linear momentum of the particle phase.