[florian.crepin]

Hi everyone,

I work on ANSYS Fluent to model a gel motion passing through a constricted channel.
I would like to create a new material for my gel with his own properties (Young’s Modulus, Poisson Ratio, Density). But when I create a new material in Fluent, the only properties that I can input are density, viscosity and others, but I can’t add the young’s modulus and poisson ratio. Is it possible to do? And how can I do?

I heard that we could use a User Defined Material Database, but on the examples I saw, I’ve never seen any Young’s modulus or Poisson ratio. Is it possible to add them? If yes, what would be the syntax?

If you have any other comments on how can I model this phenomena (gel motion through a constricted channel), it is highly appreciated.

Thank you very much in advance

[obscureed]

Hi Florian,

Fluent is a code for fluid mechanics, but Young's modulus and Poisson's ratio are structural properties, so they are not included. Fluent has some ability to model non-Newtonian behaviour, but even properties such as yield stress are modelled using viscosity, so elastic strength at zero shear is not included.

To some extent, the question can be bounced back to you: if you specify a material's Young's modulus and its viscosity, how do expect it to react to shear stress (for example)? You cannot sensibly specify both these, I think. I would recommend you look at Fluent's non-Newtonian viscosity models (such as Hershel-Bulkley) and see whether these characterisations would apply to your gel. If you need more structural behaviour than these, you need a different solver. Trying to sneak extra behaviour into User-Defined Functions is not a sensible approach here.

Best regards,
Ed

[florian.crepin]

Hi Ed,

Thank you very much for your answer.
Yes you are right it is not possible to specify both viscosity and Young's Modulus.
I tried to use a non-Newtonian viscosity model but it doesn't fit with my gel...

I think that the only way is to use another solver.
Regarding this solver, which type of solver do you think is better to use?

Thank you very much in advance

[obscureed]

Hi Florian,


Sorry, I am not an expert in other solvers. To find a sensible answer, you will first need to characterise your gel with some kind of visco-elastic model -- viscosity cannot be combined with Young’s Modulus/Poisson Ratio in any model.


Good luck!
Ed

[cae]

Hope you can get some information from this review, "Particle squeezing in narrow confinements". Microfluidics and Nanofluidics, 22(10), [120]. https://doi.org/10.1007/s10404-018-2129-2