ANSYS12.0官方培训教程 Fluent Chapter9-Advanced Physics.pptVIP

It is important to understand the relationship between the velocity viewed from the stationary and relative frames. This relationship is often called the “velocity triangle,” and can be expressed by the simple vector equation: Here, V is the velocity in the stationary or absolute frame ,W is the velocity viewed from the moving frame, and U is the frame velocity. For a rotating reference frame, U is simply Notice from the picture of the moving turbine blade that a flow approaching the blade in the x direction appears to be moving with a positive angle due to the downward motion of the blade. Once the solver, physical model, and material selections have been made, you can activate a moving reference frame in the BC panel for the fluid zones. The parameters which must be set as follows: Enter first the rotational axis origin and direction. The origin (x,y,z) corresponds to the origin of the moving frame, while the direction is a unit vector pointing in the direction of the axis. Rotation of the frame is defined using the right-hand-rule. Next, under “Motion Type”, select “Moving Reference Frame”. This indicates to Fluent that the entire cell zone is moving with the translational and rotational speeds you provide. Finally, enter the moving zone velocities – most typically a rotational velocity, though a translational velocity may be employed under special circumstances. Note that the rotational velocity may be positive or negative, a negative speed implying a sense of rotation opposite to the right hand rule. Flow boundaries require some special attention for SRF models. First, velocity inlets permit specification of velocity directions or components in either the absolute or relative frames. Use the form which is relevant to the problem at hand. Pressure inlet specifications, however, are closely tied with the velocity formulation. Specifically, if you are using the AVF, the total pressure which is entered into the GUI is the absolute total pr