Water is chosen as the working fluid in the calculation and its inlet temperature is 300 K. The tube wall of inlet region and stable region keep in a constant temperature of 310 K. The wall of outlet region is adiabatic in this calculation. By coupling and solving the governing equations above, we can know how virtual heat field affects flow organization in the tube and the theoretical model can be validated. The commercial CFD software FLUENT 6.3 is adopted in the calculation. The SIMPLEC algorithm is used for coupling the pressure and velocity equations. QUICK scheme is adopted to discretize
convection and diffusion terms. The user defined function (UDF) and user defined scalar (UDS) are utilized to solve the governing Eqs. (14) and (15). The convergent solutions are obtained when the residuals of all governing equations are less than 10