Error Message—Conjugate heat transfer solids must be meshed with more than one element
A long, thin solid object is included within a model, and heat transfer is enabled. The mesh on the solid object is fairly coarse, with only a single element across the thickness. Heat is conducted through the solid. The following error is issued:
Error: Conjugate heat transfer and two-phase flow problems must have solid regions that are more than 1 element thick
The temperature distribution is not accurate and does not appear correct. There may be very little gradient down the length of the object, and no gradient across it. The temperature values also do not appear correct.
The problem is due to the coarseness of the mesh. Solid objects that are conducting heat should be meshed with at least two elements across their thickness. This increases the overall element and node count, but it greatly improves the accuracy of the temperature distribution.
The reason is that each solid element is linear, so the temperature profile is approximated using a collection of linear line segments. Using a single element significantly reduces the accuracy of the approximation. An additional consideration is that the coarse mesh affects the temperature in adjacent fluid and solid parts as well.
Access the Mesh task, and redefine the mesh distribution on the solid to ensure that there are at least two elements across the thickness of the entire part.
Use the "Use Uniform" button on the Mesh Sizes dialog to ensure that the mesh does not become coarser in some regions of the part (and reduced to a single element). Note that you might have to coarsen the distribution after enabling Use Uniform to keep the mesh count from getting too high.