## General Mechanical

#### How to set a non-uniform initial temperature in Transient Thermal?

• zheng gong
Subscriber

Hello,

I am modeling two objects with different initial temperatures. But it is not available when I want to set the non-uniform initial temperature. I am very perplexed about this problem.

Any help will be highly appreciated!! Thanks!!!

• Erik Kostson
Ansys Employee

Hi

So do you try to import the temp. field from a steady state thermal into your transient ?

All the best

Erik

• zheng gong
Subscriber

Hello Erik,

Thanks very much for your reply. Do you mean the initial temp. field that I want to set in the transient model is the result of a steady-state thermal model? I know this method but I don't know how to do it. I am wondering why we can't directly do this in transient thermal. 😶

• Erik Kostson
Ansys Employee

These fields I think is when you want to import the temp. field from a steady state thermal into your transient (thermal also) – so you need to connect a steady to a transient thermal and they need to be the same models.

All the best

Erik

• Bill Bulat
Ansys Employee

An alternative to the procedure Erik described is to define two load steps in Details of Analysis Settings. You can turn time integration effects off for the first step, making it a steady state calculation. Apply boundary conditions that will give you the initial nonuniform temperature distribution that you seek.

Leave time integration effects on for the second step so that it becomes a transient that starts out with the non-uniform temperature calculated in step 1. You can activate/deactivate boundary conditions at the start of transient step 2 as needed to be consistent with the physical process you are simulating.

Kind regards,

Bill

• zheng gong
Subscriber

Hello Erik and Bill,

Thanks very much for your reply!  In fact, I am using the method that Bill says.

I wonder if Ansys can make it straightforward to set the initial temperature and BCs.😅😅

For example, I want to study the transient temperature changing with time in the above example. The initial temperatures are 400K(upper) and 300K(nether) respectively at t=0s. The time range that I want to study is t=0-10s. I want to know the temperature distribution during this time range....

Thanks,

Zheng