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Hello, I have built a 3D model of gas metal arc welding. As shown in the picture, the middle of the model is patched as air, and the other area is aluminium alloy. The VOF model and melting && solidification models are used to simulate the weld pool shape. The boundary conditions are simply defined as wall. The solid temperature of aluminium alloy is defined as 873K and the liquid temperature is 973K, and the initialized temperature is 300K. When I run conculation for several time steps, the shape of aluminium alloy would change as picture2 while its temperature is lower than the solid or liquid temperature.
Why can the shape of the solid material change? This problem have confused me for a long time, Can anyone help me solve this problem?