6.7 Boundary condition treatments for open system 6.7.1 Selections for outlet boundary 6.7.2 Treatment of outlet boundary condition 6.7.3 Treatment of outlet boundary condition with 6.7.4 Methods for outlet normal velocity satisfying 6.7.1 Selections for outlet boundary position 6.7.2 Treatment of B.C. without recirculation 6.7.4 Methods for outlet normal velocity to satisfy 6.8.1 Natural convection in an enclosure 6.8.2 Numerical treatments of island (孤岛) 6.8 Fluid Flow and Heat Transfer in a Closed System 6.8 Fluid Flow and Heat Transfer in a Closed system 6.8.1 Natural convection in enclosure 6. Other examples of flow in enclosure 6.8.2 Numerical treatments for isolated island