hi!

i m new in fluent....i am trying to solve the transfer of heat from cylinder wall to the fluid inside the cylinder.this is the unsteady state problem.i need to plot Tavg VS time for the fluid . can anyone help me how to solve this problem and what should be the boundry condition for this type of problem?

You say the situation is unsteady. So you select the unsteady option under solver panel. Is the wall at const Temperature or const heat flux. accordingly apply the thermal BC to the wall. is your wall moving? if yes then apply the value of motion under momentum BC. what info you have at the inlet pressure or mass flow rate/velocity. accordingly you choose the BC type for inlet and apply the value. which average temperature you are looking for? Centerline temperature or Bulk mean temperature or something else? Describe the problem extensively.

Follow a transient tutorial. This is the best way to understand the requirements.

Hi rakesh! Thanks for giving me reply for this problem....My wall is at constat tempreture and wall is not moving...can u help me to take the BC's for this problem??...i take fluid under specify continuum types as a BC's and wall under specify BS's...is this BC's help for me or not??...i need to find the average tempreture of the fluid for different time and need to plot the graph of average tempreture of the fluid vs time .

You do have provision to apply constant temperature to wall. click on thermal BC panel where by default you will have heat flux option checked on, please check temperature option there and put your value under the right side entry box. in fluent, walls are stationary by default so you dont need to change anything there. whole domain is fluid only so you have chosen it rightly. I dont understand the definition of average temp here, because average can be found out in many ways. I think you are looking for ensemble average kind of thing. which you can do by creating a desired location. then in xy plot you can plot/write the avg temp vs time.

Hope it helps