[wali]

Dear CFD Analyst,

I am doing a project work in drying process of iron ore pellet using commercial software ANSYS fluent but I am facing convergence issue in it. The nature of the problem is described in Fig.1.



The following are the steps that I followed for the modelling of the same.

Pressure based solver
Transient analysis
Eulerian method = no. of phases =4 (air, liquid, ore, vapor)
Turbulence model = kappa omwga SST
Energy equation =ON
Primary phase =air, Seconday phases= liquid, ore and vapor
Interaction= phase change = liquid to vapor
Drag : Schiller naumann
Fluid 1: Porous zone : Porosity 0.315 Under mixture tab
Heat transfer : thermal Equilibrium model : solid material : ore
Direction vector X =1, Y=0 Under air phase only
Viscous resistance = 3.33e +12 for both direction
Inertial Resistance = 1470000 for both direction
While for the rest of the phases no resistance values are applied, and applying fixed values of 0m/s for X and Y under fixed tab this is only for the ore phase.
Boundary condition:
Inlet: velocity inlet, Outlet : outflow, top and bottom : symmetry, ore surface : interior, fluid 1 and 2 region is also interior

Solution methods:
Scheme : phase coupled SIMPLE
Gradient : least square cell based
Momentum, volume fraction, turbulent kinetic energy, Specific dissipation rate : First order upwind,
Transient formulation: First order implicit
Regions Adaption is used for defining the volume fraction

Firstly for some time, the simulation is performed without the volume fraction shown in Fig.2 i.e Solution control> equation > Select only flow, turbulence and energy. For this method the solution is well converged after some iteration. (Fig.3)
Now , the situation where I am stuck right now when I select the volume fraction (fig.4) after some time of the simulation, to determine the variation of volume fraction inside the ore at this time the solution is not converged it shows: “v-ore residual is in the range of .9912” (fig.5)
Please help me how to resolve the issue.

The paper that I have used for the validation purpose:
Simulation of convective drying of a cylindrical iron ore pellet
Anna-Lena Ljung and T. Staffan Lundstro¨m
Division of Fluid Mechanics, Lulea° University of Technology,
Lulea° , Sweden, and
Kent Tano
LKAB R&D, Malmberget, Sweden






Regards
Wali