FloEFD > Viscosity as Goal

-mAx- · November 26, 2015, 03:10

Hello,
In the results, I find the goal-summary very usefull and also representative for the set up of the calculation.
But I am missing the fluid viscosity.
I always run calculations with constant viscosity (so floefd is solving the energy equation for peanuts > is there a way to deactivate the energy equation? I am not interested in the temperature distribution)
Back to my initial question: I would like to see the viscosity range in the goal-summary (excel export).
I tried to introduce a goal relating to the viscosity withot any success.
Thank you

Boris_M · November 30, 2015, 08:07

Hi Maxime,

the viscosity is part of the fluid property and changes over the temperature.
So you would need the temperature to get to that property.

What you could do is to use the data in the Engineering Database on the viscosity and put it in Excel. Create a fitting curve on it and use the equation that describes the curve in an equation goal with the temperature at the location you are interested in from another goal as a goal dependency in the equation goal to calculate the dynamic viscosity of the fluid.

Would that work for you?

Boris

-mAx- · November 30, 2015, 08:21

yes it should work, but as I said, I don't work with temperature.
In the Fluid Database I only create fluid with constant viscosity (independantly from temperature) (One fluid per temperature, for instance oil at 0°C / oil at 20°C and so on)
Doing that I don't look after the temperature in the BC.
I thought we could also add the viscosity as a Goal just like the density (which is also a fluid property)

Boris_M · November 30, 2015, 08:44

Ok, I understand. So you have just a fixed value for isothermal simulations. I thought any heat transfer into the solids but maybe mixing fluids with different temperatures and therefore varying viscosities.

So you just want to use the fixed value in a calculation such as Re number but need to enter it manually all the time. Is that what your issue is?

Boris

-mAx- · November 30, 2015, 08:51

exactly, only isothermal with only one phasis.
At the end I only want to have my constant viscosity as goal (I know it is a given parameter), just to be sure I was running with right viscosity range

November 26, 2015, 03:10	FloEFD > Viscosity as Goal	#1
-mAx- Super Moderator Maxime Perelli Join Date: Mar 2009 Location: Switzerland Posts: 3,297 Rep Power: 41	Hello, In the results, I find the goal-summary very usefull and also representative for the set up of the calculation. But I am missing the fluid viscosity. I always run calculations with constant viscosity (so floefd is solving the energy equation for peanuts > is there a way to deactivate the energy equation? I am not interested in the temperature distribution) Back to my initial question: I would like to see the viscosity range in the goal-summary (excel export). I tried to introduce a goal relating to the viscosity withot any success. Thank you __________________ In memory of my friend Hervé: CFD engineer & freerider

November 30, 2015, 08:21		#3
-mAx- Super Moderator Maxime Perelli Join Date: Mar 2009 Location: Switzerland Posts: 3,297 Rep Power: 41	yes it should work, but as I said, I don't work with temperature. In the Fluid Database I only create fluid with constant viscosity (independantly from temperature) (One fluid per temperature, for instance oil at 0°C / oil at 20°C and so on) Doing that I don't look after the temperature in the BC. I thought we could also add the viscosity as a Goal just like the density (which is also a fluid property) __________________ In memory of my friend Hervé: CFD engineer & freerider

November 30, 2015, 08:51		#5
-mAx- Super Moderator Maxime Perelli Join Date: Mar 2009 Location: Switzerland Posts: 3,297 Rep Power: 41	exactly, only isothermal with only one phasis. At the end I only want to have my constant viscosity as goal (I know it is a given parameter), just to be sure I was running with right viscosity range __________________ In memory of my friend Hervé: CFD engineer & freerider

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November 30, 2015, 08:07		#2
Boris_M Disabled Join Date: Jul 2009 Posts: 616 Rep Power: 23	Hi Maxime, the viscosity is part of the fluid property and changes over the temperature. So you would need the temperature to get to that property. What you could do is to use the data in the Engineering Database on the viscosity and put it in Excel. Create a fitting curve on it and use the equation that describes the curve in an equation goal with the temperature at the location you are interested in from another goal as a goal dependency in the equation goal to calculate the dynamic viscosity of the fluid. Would that work for you? Boris

November 30, 2015, 08:44		#4
Boris_M Disabled Join Date: Jul 2009 Posts: 616 Rep Power: 23	Ok, I understand. So you have just a fixed value for isothermal simulations. I thought any heat transfer into the solids but maybe mixing fluids with different temperatures and therefore varying viscosities. So you just want to use the fixed value in a calculation such as Re number but need to enter it manually all the time. Is that what your issue is? Boris