相变凝结蒸发，源项vof-udf，定义连续性方程，能量方程，动量方程中的质量源项，能量源项和动量源项(fluent1.Boiling Tutorial: Heat and Mass Transfer with the Mixture Model 2.Tutorial: Horizontal Film Boiling 3.Tutorial: Modeling Uniform Fluidization in a Two Dimensional Fluidized Bed)

udf中动量编写较为稀少，x方向的编写如程序所见，其余方向的编写可按程序同理编写。(Momentum writing in UDF is relatively rare. The writing in X direction is as seen in the program. The writing in other directions can be done in the same way as that in the program.)