对水面的自由表面是怎么处理,请问

junelu

对水面的自由表面是怎么处理,如何设置

phoenics

有自由表面模型

phoenics

Question: - What are the free surface capabilities in PHOENICS?
Answer:
PHOENICS has at least six features which have been used for the simulation of flows with free surfaces, namely:
(1)    Height-of-liquid (HOL) method;
(2)    Scalar-equation method (SEM);
(3)    IPSA, with high interphase friction and an interface sharpening device;
(4)    Moving porosities, with a blocked region adapting to the shape of a liquid surface;
(5)    Moving body-fitted coordinates; and
(6)    Surface tracking by means of moving particles.
Which method should be chosen depends on the type of application area. CHAM can offer advice if comprehensive information is supplied by the user about the kinds of free-surface problems for which he is seeking solutions. This information should include answers to at least the following questions:
(a) Is the flow steady or unsteady?
(b) Is the flow 1D, 2D or 3D?
(c) Are the fluids gases, liquids or both?
(d) Does mass cross the interface, and, if so, in accordance with what law?
(e) Does the interface remain approximately horizontal or approximately vertical?
(f)  Are there any other known limitations, for example - no overturning?
(g) Is gravity (or some other body force) active?
(h) Is one, or are both, fluids, in thermal contact with a solid obstruction to the flow?
(i)  Is either fluid compressible?
(j)  Is the user interested in a single example or in a class of problems?
(k) If the user is interested in a class, what is the extreme range conditions contained in the class?
Some technical comments on the various methods are:
SEM is likely to be expensive in computer time as it needs to be run as a transient, and requires small time steps to combat numerical mearing of the interface (free surface), and to maintain numerical stability.
HOL is more economical than SEM, but may have to be run as a transient in order to obtain convergence. In addition, this method does not allow any overturning of the interface.
IPSA involves solving twice as many equations as the other methods unless run in equal-velocity mode, i.e. one set for the liquid phase and one for the gas. The methods will need to be run as a transient if the interface-sharpening device DONACC is used to avoid numerical smearing of the interface.