Hi Arun,

You may want to use the granular Euler-Euler model in Fluent instead - there you can define the phase properties of the secondary Eulerian phase (i.e. the copper nano particles) to be solid material. Set up your case and materials as usual and then find the granular option under Define -> Phases -> e.g. "phase-2" -> Edit -> option 'granular'. Under properties, you can define the parameters and models to be used for packing limit, granular viscosity, elasticity modulus, solid pressure etc. for your particles. But I recommend to check the user guide for details about the numerics first.

Last but not least: I guess that the momentum exchange between the primary liquid phase and your nano particles is very small - that's why: is it really required to use an Euler-Euler approach?

Hope this helps.

Regards,

Stephan

Hi Arun,

You may want to use the granular Euler-Euler model in Fluent instead - there you can define the phase properties of the secondary Eulerian phase (i.e. the copper nano particles) to be solid material. Set up your case and materials as usual and then find the granular option under Define -> Phases -> e.g. "phase-2" -> Edit -> option 'granular'. Under properties, you can define the parameters and models to be used for packing limit, granular viscosity, elasticity modulus, solid pressure etc. for your particles. But I recommend to check the user guide for details about the numerics first.

Last but not least: I guess that the momentum exchange between the primary liquid phase and your nano particles is very small - that's why: is it really required to use an Euler-Euler approach?

Hope this helps.

Regards,

Stephan

Thanks for your response

But when i tried the Eulerian -langragian granular model dissimilar to the single phase model i am not able to plot wall fluid properties in XY plot

First, what I described is not an Euler-Lagrange model, but an Euler-Euler model with specifics for a granular (solid) phase.

Second, which "wall properties" do you want to plot in a XY plot? With the Euler-Euler granular model it is possible to plot wall fluxes, density and viscosity for each phase - so very similar to the single-phase modelling. I'm using ANSYS 17.0 now, but I'm rather sure that it has been possible with previous versions too.

I want to plot the pressure(static pressure) and wall fluxes such as skin friction coefficient & surface heat tranfer coefficient

In my Fluent version, it is possible to plot the skin friction coefficients for each of the phases, the surface heat transfer coefficient of the mixture, the static pressure of the mixture and the dynamic and total pressures for each of the phases (so it should be possible to calculate the static pressure for the individual phases as well, but it should give the same value as for the mixture since the phases share the same pressure field). Again, I set the Euler-Euler multiphase model and defined the secondary phase to be granular as explained above (no Lagrange modelling required). I couldn't check if the available values give meaningful values since I didn't start a simulation (and I probably won't in the near future) and I don't know about previous version of ANSYS Fluent. Hope this helps.

Stephan

Hi dear Buradi,

Why don't you try OpenFoam? We have solvers can simulate Eulerian-Eulerian multiphase flows.

Dear Ehsan Khavasi, Thank you so much for your suggestion. I will go through OpenFoam and I will Try this.

Thank you

I am using euler euler two phase flow in comsol multiphysics.but i can't set solid viscosity ( mud).can u please help me. What does solid viscosity mean?In my equation i need a term which is the ratio of kinematic viscosity of nanofluid over the paticle.but how can i get the solid particle kinematic viscosity? I know kinematic viscosity is the ratio of ( mu/ rho). But how can i get mu for solid particle? My simulation is for water and cu nano particle.

Hi Arun P jose, I am facing same problem. If I set nanoparticles as granular material, then how to set granular viscosity, solid pressure etc? Have you solved the problem?

Hi Saptarshi,

Granular Viscosity in a Eulerian-Eulerian mixture model indicates the sum of kinetic, collisional and frictional viscosity components for the solid particles.

In general, kinetic viscosity is calculated using an expression given by Syamlal et.al from [1] or Gidaspow et. al [2] depending upon the particle volume fraction and particle diameter used.

Collisional viscosity is modelling by an expression given by Gidaspow et.al [2]

Frictional viscosity is calculated by an expression given by D.G.Schaeffer [3]. This frictional velocity is significant only when the volume fraction is closer to the packing limit (63%). In nanofluids, we generally consider a volume fraction less than 5% due to practical constraints. Hence, frictional viscosity component is generally ignored for nanofluids.

Solid pressure indicates the pressure gradient term in the fluid-solid momentum equation. It is generally estimated by a model proosed by Lun et. al [4]

In order understand more about these concepts, you can read on kinetic theory of granular flow.

[1] M. Syamlal, W. Rogers and T. J. O’Brien. MFIX Documentation: Volume1, Theory Guide>. National Technical Information Service, Springfield, VA. DOE/METC-9411004, NTIS/DE9400087, 1993.

[2] D. Gidaspow, R. Bezburuah, and J. Ding. "Hydrodynamics of Circulating Fluidized Beds, Kinetic Theory Approach". In Fluidization VII, Proceedings of the 7th Engineering Foundation Conference on Fluidization. 75–82. 1992.

[3] D. G. Schaeffer. "Instability in the Evolution Equations Describing Incompressible Granular Flow". J. Diff. Eq. 66. 19–50. 1987.

[4] C. K. K. Lun, S. B. Savage, D. J. Jeffrey, and N. Chepurniy. "Kinetic Theories for Granular Flow: Inelastic Particles in Couette Flow and Slightly Inelastic Particles in a General Flow Field". J. Fluid Mech. 140. 223–256. 1984.

@Deepak selvakumar R Here i am not able to understand how inlet velocity is calculated? based on water properties or mixture properties?

the inlet velocity should be calculated based on mixture properties.

Hi Deepak Selvakumar R Thanks for your valuable suggestions. As per your suggestion I tried to use Granular model for nanoparticle. Still I have some confusions. So my question is-

(1) During selection of a material for phase 2, should I define a new material?

(2) Whether this new material should be defined as fluid material or solid material?

(3) If I define a new material in using defined database, how to input the properties of particles? Whether I have to follow your previous suggestion of volume weighted average method?

Kindly help me. Thanks in advance