Hi,everyone Thanks in advance for your help! I want to define a variable density which varies with temperature for solid material. Firstly, I write a udf for it, but soon i found that for solid material' density it donesnot support udf! How should I do?

if you change density of solid the volume should be changed accordingly to conserve mass (thermal expansion). In order to calculate thermal expansion strains and stresses software (code) have to solve elasticity problem with corresponding boundary conditions. I assumed you tried this with fluent. Fluent does not solve elasticity problems, for that you can use ANSYS or ABAQUS.

Thanks Alex Chirokov, but it will make the problem difficult! I just want to define a solid density that varies with temperature, could i define a liquid density where i define its viscosity infinite that it will not move£¿

hi neng_ren, your question is interesting but I am still a little confused about it. Does the density variation in the solid region affect heat trafsering or other things in the flow? if not, I think you can leave this to postprocessing. good luck.