Fluent12.0之空化模型介绍
Cavitation Models A liquid at constant temperature can be subjected to a decreasing pressure, which may fall below the saturated vapor pressure. The process of rupturing the liquid by a decrease of pressure at constant temperature is called cavitation. The liquid also contains the micro-bubbles of noncondensable (dissolved or ingested) gases, or nuclei, which under decreasing pressure may grow and form cavities. In such processes, very large and steep density variations happen in the low-pressure/cavitating regions. This section provides information about the following three cavitation models used in ANSYS FLUENT. [*]Singhal et al. model: You can use this model to include cavitation effects in two-phase flows when the mixture model is used. This is also known as the Full Cavitaton Model, which has been implemented in ANSYS FLUENTsince Version 6.1.[*]Zwart-Gerber-Belamri model: You can use this model in both the mixture and Eulerian multiphase models.
[*]Schnerr and Sauer model: This is the default model. You can use this model in both the mixture and Eulerian multiphase models.The following assumptions are made in the standard two-phase cavitation models: [*]The system under investigation must consist of a liquid and a vapor phase.
[*]Mass transfer between the liquid and vapor phase is assumed to take place. Both bubble formation (evaporation) and collapse (condensation) are taken into account in the cavitation models.
[*]The cavitation models are based on the Rayleigh-Plesset equation, describing the growth of a single vapor bubble in a liquid.
[*]In the Singhal et al. model, noncondensable gases have been introduced into the system. The mass fraction of the noncondensable gases is assumed to be a known constant.
[*]The input material properties used in the cavitation models can be constants, functions of temperature or user-defined.The cavitation models offer the following capabilities: [*]The Singhal et al. model can be used to account for the effect of noncondensable gases. The Zwart-Gerber-Belamri and Schnerr and Sauer models do not include the noncondensable gases in the basic model terms.
[*]The Zwart-Gerber-Belamri and Schnerr and Sauer models are compatible with all the turbulence models available in ANSYS FLUENT.
[*]Both the pressure-based segregated and coupled solvers are available with the cavitation models.
[*]They are all fully compatible with dynamic mesh and non-conformal interfaces.
[*]Both liquid and vapor phases can be incompressible or compressible. For compressible liquids, the density is described using a user-defined function. See the separate UDF Manual for more information on user-defined density functions. 很好很强大 默认的已不是Singhal的模型，Singhal模型用起来还是比较麻烦的
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