[oozcan]

Hi all,

I am working on heat tansfer over 3d mould equipments.

First, I have allowed to flow and turbulence equations to be get converged. Then, energy eq. has been activated. some fluctuations has happened in volumetric flow rate of inlet. How could it be possible? velocity and cross section of inlet side are constant. (why does density change)

Kind Regards,

[LuckyTran]

What is your equation of state?

A velocity inlet only specifies the velocity and temperature. Pressure and density can still change at a velocity inlet. If you are using the ideal gas EOS for example, it could result is changing massflow at the inlet.

[oozcan]

Originally Posted by LuckyTran

What is your equation of state?

A velocity inlet only specifies the velocity and temperature. Pressure and density can still change at a velocity inlet. If you are using the ideal gas EOS for example, it could result is changing massflow at the inlet.

Well,thank you for remembering some past exclusive ''fluid dynamics'' information.

I have defined ''incompressible ideal gas ''

mass flow rate difference at inlet and outlet must be 0 ideally (continuity equation in a way).Thus, volumetric flow rate and density can change with temperature changes at inlet or outlet.

Well, you can find attached photo, and as you can see, temperature changes after some few iterations because of activating energy equation. The question I ask is why density changes as energy equation has been activated?

Inlet temperature is boundary condition and I have defined a constant value. That is why density must be constant as well, volumetric flow rate and mass flow rate, respectively. I am confused

and I just wonder that what does EOS, and equation of state?

[LuckyTran]

I was not paying attention and started talking about mass flow rate which is not the problem.

You are right the volumetric flow rate is fixed (it's just a velocity and has nothing to do with density and temperature).

Can you check the way you are calculating volumetric flow rate? It is not calculated in Fluent is it? Maybe you made a mistake?

[oozcan]

Originally Posted by LuckyTran

I was not paying attention and started talking about mass flow rate which is not the problem.

You are right the volumetric flow rate is fixed (it's just a velocity and has nothing to do with density and temperature).

Can you check the way you are calculating volumetric flow rate? It is not calculated in Fluent is it? Maybe you made a mistake?

Volumetric flow rate = Velocity components x Wet area.

volumetric flow rate, mass flow rate, density are compatible with calculations in hand until energy equation is activated.

Wet area, velocity are constant, volumetric flow rate must be constant,as well. I still dont understand why volumetric flow rate changes.

[oozcan]

Originally Posted by LuckyTran

I was not paying attention and started talking about mass flow rate which is not the problem.

You are right the volumetric flow rate is fixed (it's just a velocity and has nothing to do with density and temperature).

Can you check the way you are calculating volumetric flow rate? It is not calculated in Fluent is it? Maybe you made a mistake?

I have defined ''velocity_inlet'' as BC and specified 1.5 m/s and 300 K temperauture. As you can see attached screenshoots, velocity magnitude in inlet face is ok, still constant. But volumetric flow rate changes with temperature in spite of constant temperature value I have specied in BC. Accordingly, density changes in same way (that is already sense).

How could it be?

Moreover, I have specified turbulence intensity and hydraulic diameter values by calculating in hands.