Learning Forum

[DEBA]

Respected Sir/Madam 

I am trying to do a 2d blood flow model .PERIPHERIAL REGEION IS NEWTONIAN AND CORE REGEION IS NON-NEWTONIAN ( I AM USING CASSON MODEL). 

MY QUERY

1) WHICH METHOD SHOULD I USE ?

2) HOW I WILL DIVIDE THIS TWO REGEION & HOW I WILL PROCEED TWO MODEL TWO FLUID FLOW TO GATHER ( NEWTONIAN AND CASSON)

3) HOW I WILL DEFINE IN FLUENT CASSON FOR CORE REGEION AND NEWTONIAN FOR PERIPHERIAL REGEION  PLEASE HELP  

[Rob]

Hi,

It's not usual to try and set viscosity to use different models in the same zone: how do you intend to match the values between the core and peripheral sections? I'd suggest looking through some of the references to see what others have done: I've used the Casson & Carreau-Yasuda models simulate blood in a variety of systems. 

Cheers,
Rob

 

[Raef.Kobeissi]

I agree with Rob, check the Casson & Carreau-Yasuda model.

 

Regards

[Rob]

To clarify (rather than editing my earlier comment), it's two models: Casson and separately Carreau-Yasuda.  Both are valid but there's some debate in literature over whether you apply one or other to venous or arterial flows, I wouldn't use both at once!  

 

 

[DEBA]

actually sir i have written udf code for casson model i want use casson model

My aim is to see dispersion phenomenon. As you have mentioned sir you have worked on casson & Carreau-Yasuda model .if you please give me paper and refernce it will be helpful to me.

[DEBA]

Sir My aim is to see dispersion phenomenon,sir i have written udf code for casson model i want use casson model..if you please give me paper and refernce it will be helpful to me.

[Rob]

Casson model is fine.  You don't need to set the viscosity near the wall, the velocity profile (and shear) should push the model towards one of the limits. Just make sure there is a good near wall mesh using inflation layers to get the most out of the viscosity model.  

Hopefully this is enough to help, and the community can assist further: as ANSYS staff we're very limited in our support scope beyond general assistance with the software and this is starting to get a bit too specific for the staff team. 

 

[DEBA]

Sir my main query is that " How will  i  use for flow  simultanously upper layer newtonian and lower layer non newtonian " please help this 

[Amine Ben Hadj Ali]

How are the regions / layers separated from on another?

[DEBA]

Sir i have attached picture here .I am trying to do model as blood as two phase .From  axis 80% radius  ( plug & core) behaves as  Non Newtonian region due to suspension of RBC in plasma. And  from 80% it behaves like Newtonian fluid.Property of Newtonian fluid known to me and for non newtonian fluid i have written udf. 

My question to you how i put  property in different layer  that is non Newtonian property in non Newtonian region and Newtonian property in Newtonian region means how i will define property in two different zone and simulate

[Amine Ben Hadj Ali]

If the layers are separated from one another then you can assign each layer its own material. If the layer are not separated and the regions would diffuse or mix with another then you can use a species transport model be defining a mixture of all three materials. the viscosity of the mixture would be then set as harmonic average or volume weighted mixing.