how to change richardson number in fluent??

azorit · August 16, 2017, 07:06

hi . can anyone help me how change RICHARDSON NUMBER in fluent?

my geometry is a T-shaped enclosure.

CeesH · August 16, 2017, 08:47

The same as you would do it without FLUENT.
You have the choice to change gravity, density, or velocity. Of course, do check if other relevant numbers change when toying with any of these.

azorit · August 16, 2017, 09:16

Quote:

Originally Posted by CeesH

The same as you would do it without .
You have the choice to change gravity, density, or velocity. Of course, do check if other relevant numbers change when toying with any of these.

tanx for helping me. so in ri=Gr/Re^2 , for example i want fix my richardson number at 0.2 . and my Re number is 500 .so i have to calculate Gr number and change density ??

CeesH · August 16, 2017, 09:22

If you want to change Ri while keeping Re constant, change gravity (which doesn't influence Re)

azorit · August 16, 2017, 10:28

Quote:

Originally Posted by CeesH

If you want to change Ri while keeping Re constant, change gravity (which doesn't influence Re)

dear CeesH what about thermal expansion coefficient ? can i change it too?

LuckyTran · August 16, 2017, 11:39

Note that changing density will also change the Reynolds number.

Thermal expansion coefficient is a fluid/material property. However, if you choose certain equations of state, it may not be available to you. If you take pressure, temperature as state variables, then the thermal expansivity of a gas and its density are interconnected. You really need to consider what your equation of state is. But in general, changing the thermal expansion coefficient does change the Reynolds number.

azorit · August 16, 2017, 12:25

Quote:

Originally Posted by LuckyTran

Note that changing density will also change the Reynolds number.

Thermal expansion coefficient is a fluid/material property. However, if you choose certain equations of state, it may not be available to you. If you take pressure, temperature as state variables, then the thermal expansivity of a gas and its density are interconnected. You really need to consider what your equation of state is. But in general, changing the thermal expansion coefficient does change the Reynolds number.

dear LuckyTran , my model is two phase mixture , primary phase is water and secondary is al2o3 , and i want to calculate my problem in three richardson value (0.1 , 1 , 10) and my Re number is 500 . now my question is by changing in which parameter i get desire Ri number?

CeesH · August 17, 2017, 04:09

Well sure you can change the thermal expansion coefficient; again, in principle you can change any parameter present in Ri. However, you should ensure that you are not changing other relevant numbers simultaneously. Since you are planning to keep Re constant, density and velocity are unsuitable. As LuckyTrans states, thermal expansion is unwise, too.

So again, that leaves gravity. What do you have against changing that?

August 16, 2017, 07:06	how to change richardson number in fluent??	#1
azorit New Member Mohamad Join Date: Aug 2017 Posts: 6 Rep Power: 8	hi . can anyone help me how change RICHARDSON NUMBER in fluent? my geometry is a T-shaped enclosure.

August 16, 2017, 08:47		#2
CeesH Senior Member Cees Haringa Join Date: May 2013 Location: Delft Posts: 607 Rep Power: 0	The same as you would do it without FLUENT. You have the choice to change gravity, density, or velocity. Of course, do check if other relevant numbers change when toying with any of these. azorit likes this.

August 16, 2017, 09:22		#4
CeesH Senior Member Cees Haringa Join Date: May 2013 Location: Delft Posts: 607 Rep Power: 0	If you want to change Ri while keeping Re constant, change gravity (which doesn't influence Re) azorit likes this.

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August 16, 2017, 11:39		#6
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,674 Rep Power: 65	Note that changing density will also change the Reynolds number. Thermal expansion coefficient is a fluid/material property. However, if you choose certain equations of state, it may not be available to you. If you take pressure, temperature as state variables, then the thermal expansivity of a gas and its density are interconnected. You really need to consider what your equation of state is. But in general, changing the thermal expansion coefficient does change the Reynolds number.

August 17, 2017, 04:09		#8
CeesH Senior Member Cees Haringa Join Date: May 2013 Location: Delft Posts: 607 Rep Power: 0	Well sure you can change the thermal expansion coefficient; again, in principle you can change any parameter present in Ri. However, you should ensure that you are not changing other relevant numbers simultaneously. Since you are planning to keep Re constant, density and velocity are unsuitable. As LuckyTrans states, thermal expansion is unwise, too. So again, that leaves gravity. What do you have against changing that?