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Old   November 23, 2014, 09:49
Default Nanofluid simulation
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Mansoor Ahmed
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Nanofluid simulation using ansys fluent

Hi everyone
I m simulating nanofluids as single phase. I have updated the entire properties of fluid with that of nanofluid. But I don't know how to enter nanoparticle size as I want to simulate the offect of nano particle size on heat transfer capability and pressure drop characteristics.kindly help me in this regard

Last edited by wyldckat; November 23, 2014 at 10:18. Reason: accidental double post
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Old   November 24, 2014, 07:44
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Cees Haringa
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Hi,

If you are running a single-phase simulation, you cannot set particle size, since there are no particles. You will need to alter the heat transfer parameters based on empirical correlations in that case; similar to altering the viscosity when you are considering a particulate flow as single phase. Or am I not understanding you correctly?

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Old   November 24, 2014, 10:39
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Lucky Tran
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Keep in mind that many assumptions are made with respect to fluid particles in the fluid model.

Simulating nanoparticles dispersed in a fluid (which is multi-phase problem) is different from simulating a fluid with nanoparticles with effective properties (the single-phase problem). Example, in the fluid flow of air or water, we never talk about the size of the air/water molecules).
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Old   November 25, 2014, 00:33
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Mansoor Ahmed
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thanks to both of you.
so does it mean that we can not study the effect of particles size on heat transfer enhancement if we are considering nanofluid as a single phase flow??
I have read in a research paper that if we consider the effect of brownian motion, then effective thermal conductivity is composed of static part (maxwell theory) and dynamic part (brownian motion), In the dynamic part we have nanoparticle diameter.see picture for detail:
thanks again for your time
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Old   November 25, 2014, 02:07
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Lucky Tran
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Quote:
Originally Posted by engrmansoor2534 View Post
thanks to both of you.
so does it mean that we can not study the effect of particles size on heat transfer enhancement if we are considering nanofluid as a single phase flow??
I have read in a research paper that if we consider the effect of brownian motion, then effective thermal conductivity is composed of static part (maxwell theory) and dynamic part (brownian motion), In the dynamic part we have nanoparticle diameter.see picture for detail:
thanks again for your time
The work proposes an equation for calculating an effective thermal conductivity which has contributions from nanoparticle diameter. Ok. But that means once you put in the effective thermal conductivity in Fluent you are done. It's now a single phase flow with an effective thermal conductivity. The fluid doesn't know that there are nanoparticles.

Once you put in effective bulk properties that "account" for the nano particle behavior, you don't talk about nano particles sizes anymore, in the same sense that we stop talking about molecular sizes of individual molecules when we talk about density, thermal conductivity, viscosity, etc.

So I am confused. If you were able to enter the effective properties of the nanofluid, what exactly is the problem here? Did you perhaps put the incorrect property? The statement of your question also states that you have already solved the problem.
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Old   November 25, 2014, 02:48
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thanks LuckyTran
I got your point. I am now going to simulate the flow with the effective properties I calculated and will consult you in case of any problem.
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