[parmeshwar]

Problem defination:

Annular water domain is created due to glass and steel pipe of which glass is having dia more than that of steel.glass pipe has 5mm thickness and steel pipe of 1mm thickness.Water is closed from both the ends and no heat is transferred from ends of pipe(water, steel glass).Inner surface of steel pipe is open to atmosphere and outer surface of glass pipe is exposed to radiation intensity of 800W/m2. Length of domain is 1m.Initial Temperature of water is 300K.

I have to find change in temperature of water and radiative heat flux distribution in the water from the glass upto steel.

for solving this problem in fluent I have to use DO(discrete radiation) model.

so,
1. what should be the boundary conditions for this problem?
2. How radiation heat flux is to be applied on glass outer surface?
3. Is there any need of considering air domain as inner surface of steel is open to atmosphere?
4. How to set initial temperature of water as it is closed from both the ends?

[LuckyTran]

Originally Posted by parmeshwar

1. what should be the boundary conditions for this problem?
2. How radiation heat flux is to be applied on glass outer surface?
3. Is there any need of considering air domain as inner surface of steel is open to atmosphere?
4. How to set initial temperature of water as it is closed from both the ends?

1. This should be part of your problem definition. Until you have this answered, you have not completed your problem definition. It's up to you.
2. This is answered by your boundary conditions and initial conditions (which are part of your problem definition). The rest is handled by physics.
3. I think no. Since radiation does not penetrate the steel. But it is up to you want to include the the heat transfer in this region.
4. The initial temperature has nothing to do with boundary conditions. The initial temperature is specified via the initial conditions / initialization.

[parmeshwar]

Originally Posted by LuckyTran

1. This should be part of your problem definition. Until you have this answered, you have not completed your problem definition. It's up to you.
2. This is answered by your boundary conditions and initial conditions (which are part of your problem definition). The rest is handled by physics.
3. I think no. Since radiation does not penetrate the steel. But it is up to you want to include the the heat transfer in this region.
4. The initial temperature has nothing to do with boundary conditions. The initial temperature is specified via the initial conditions / initialization.

Thanks for reply,

I have some more doubts as follows

1.I have modelled glass and steel domain along with water, Is this right way? OR can I use shell conduction method for glass and steel.

2. for first case in (1) I have applied radiation heat flux of 800W/m2 on the outer surface of glass in the radiation tab with beam direction in Y direction.Inlet and outlet BC of water as inlet velocity and pressure outlet respectively.and convection on inner surface of steel. Is this ok for my problem OR am I missing something in this?