Thermomechanical analysis

hi I have entered all the temperatures in the various passage sections but when I go to simulate it tells me that:
“Your analysis does not contain a sufficient set of constraints and would likely fail. Please review your simulation setup before starting the analysis and make sure your model is sufficiently constrained by boundary conditions.”. so in a nutshell I did not understand what the simulator needs to start the simulation. if anyone can help me with this i thank him in advance
https://www.simscale.com/workbench/?pid=7074487650232377579&mi=spec%3A67378c71-7c35-4d6e-a0ec-59558de31432%2Cservice%3ASIMULATION%2Cstrategy%3A627&ps=analysis%2FboundaryConditions%2F10

Hello, and thank you for using the Forum. Since this is now a Thermomechanical simulation, you’ll need both thermal and mechanical boundary conditions to constrain the simulation. In the current application, only the thermal boundary conditions are applied so the model is under-constrained. In other words, model is free to move in space at the moment.

This section presented under Thermomechanical documentation may help you understand the issue better and solve it.

Hope this helps.