There is one large eddy on the left hand side at the downstream end at the dam and it reaches half way to the upstream end of the model. On the right hand side there are two large eddies in the downstream part and one small eddy in the upstream end. MATHEMATICAL MODELLING Computation method The mathematical model. The PHOENICS program code, which is a finite volume code, is used for the calculations. The calculations are carried out for steady state conditions and the result should be considered as a time average of the flow field. Time dependent phenomena such as oscillating eddies can not be seen in the result In the 2-D case the pressure and the two velocities are calculated. A constant effective viscosity model is used as the turbulence model. The 2-D calculations are made in prototype scale. turbulence model in the 3D-calculations the PHOENICS standard model is used. The pressure, the three velocities and the

doi:10.1201/9781482286809-56

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There is one large eddy on the left hand side at the downstream end at the dam and it reaches half way to the upstream end of the model. On the right hand side there are two large eddies in the downstream part and one small eddy in the upstream end. MATHEMATICAL MODELLING Computation method The mathematical model. The PHOENICS program code, which is a finite volume code, is used for the calculations. The calculations are carried out for steady state conditions and the result should be considered as a time average of the flow field. Time dependent phenomena such as oscillating eddies can not be seen in the result In the 2-D case the pressure and the two velocities are calculated. A constant effective viscosity model is used as the turbulence model. The 2-D calculations are made in prototype scale. turbulence model in the 3D-calculations the PHOENICS standard model is used. The pressure, the three velocities and the

ABSTRACT

This BFC-grid is not orthogonal. The calculation program does not perform well if a cell is too nonorthogonal. Steep depth variations can cause highly nonorthogonal cells and that makes it impossible for the program to converge. In order to prevent this problem the bottom level of the grid is lowered and the correct geometry is created by blocking off cells or preventing flow through one or more cells close to the bottom as shown in figure 4 below. Variations in the horizontal geometry can be handled in the same way. This method has been used to describe the inlet and spillway shapes for this calculation.