I am working on nano particle in Ansys Fluent. I want to know which models can be used in simulation. Is DPM okay?
The discrete phase model (DPM) could work in cases where solid particles or liquid droplets are concerned. However, when it comes for suspensions like Nanofluids you should consider that the underlying physics is not well understood yet. Nanofluids and/or nanoparticle motion is a multivariable system that is primary investigated through Molecular Dynamics Simulation (MDS) instead of CFD. You may try to approach this kind of problems with Fluent, but your solution will be regarded as a first, highly uncertain with lots of assumptions one.
Dear Somanath Nirali
The model that should be used for simulation depends on the problem. For low concentrations (especially lower than 5%), the simplest model (i.e. the mixture model) can be used. In this model you only need to define the effective properties (like thermal conductivity and kinematic viscosity). Then you can treat this fluid, with modified properties, as a single-phase conventional fluid.
Cheers
The discrete phase model (DPM) could work in cases where solid particles or liquid droplets are concerned. However, when it comes for suspensions like Nanofluids you should consider that the underlying physics is not well understood yet. Nanofluids and/or nanoparticle motion is a multivariable system that is primary investigated through Molecular Dynamics Simulation (MDS) instead of CFD. You may try to approach this kind of problems with Fluent, but your solution will be regarded as a first, highly uncertain with lots of assumptions one.
I found Fluent DPM very weak in predicting Brownian motion of nanoparticles. it's better to use a scaler transport equation instead.
if the fluid is homogeneous and there is no slip velocity between the nanoparticle and the fluid then you can model it with single phase model( valid for laminar and turbulent) and model the nanoparticle as temperature dependent in a UDF
1) For low volume fraction, single-phase approach (replacing the properties) will work fine.
2) Discrete phase modelling is more realistic. It uses a Lagrangian approach in which each particle is tracked. But, it is computationally very much expensive. Almost impossible for higher volume fractions.
3) Two Phase Flow Models (Continuum models - Eulerian, Mixture, VOF) use an Eulerian approach in which the volume fraction of each phase is calculated explicitly in each control volume is more realistic than single-phase approach but less realistic than the DPM. It is more computationally expensive than single-phase approach and less expensive than DPM.
Hence, depending upon your requirements you can choose the modeling approach.
In general,
If we are interested only in the effects of volume fraction of nanoparticles -> Single-phase approach.
If we are interested in the effects of slip velocity and thermal in-equilibrium between the phases -> Two-Phase modeling.
If we are interested in individual nanoparticle behavior -> DPM.
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