Model Inputs and Multiphysics Couplings in the COMSOL Multiphysics Reference Manual
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The Dynamic viscosity, pure dispersed phase μd (SI unit: Pa·s) field is available when Liquid droplets/bubbles is selected as the Dispersed phase in The Euler-Euler Model Interfaces.
The default uses values From material. The value of the viscosity is then the value defined for the material selected in the Materials section for the dispersed phase. For User defined define a different value or expression.
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For Krieger type, select an option for Maximum packing concentration. The default is to use = 1.0 for droplets and bubbles and = 0.62 for particles. Select User defined to enter another value or expression for .
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For User defined enter a value or expression for the Mixture viscosity. The default expression corresponds to the Krieger type viscosity with maximum packing equal to 0.62.
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The Schiller-Naumann is valid for dispersed, rigid spheres and can be used for particle Reynolds numbers less than approximately 2.5·105. The Schiller-Naumann model is a general purpose model for diluted flows.
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The Hadamard-Rybczynzki is appropriate for diluted flows at low Reynolds numbers.
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The Ishii-Zuber model can for solid particles be regarded as a generalization of the Schiller-Naumann model in that it can be used also for dense flows. For droplets and bubbles, the Ishii-Zuber model also takes deformation of the fluid particles into account. The deformation depends on the Surface tension coefficient, σ. Use a predefined expression, select Library coefficient, liquid/gas interface or Library coefficient, liquid/liquid interface. Then select an option from the list that displays below (for example, Water/Air, Glycerol/Air and so forth). For User defined enter a value or expression for the surface tension coefficient σ (SI unit: N/m).
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The Gidaspow model describes the drag force coefficient for dispersed phase flows for all concentrations of the dispersed solid, including high concentrations.
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The Haider-Levenspiel model describes non-spherical particles for low and moderate particle Reynolds numbers. Enter a value between 0 and 1 for the Sphericity Sp (dimensionless).
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The Tomiyama et al. model describes the drag for diluted droplets and bubbles for any particle Reynolds number. The correlation is available in three versions, Pure fluid, Slightly contaminated fluid and Contaminated fluid. The Tomiyama et al. model depends on the Surface tension coefficient, σ that is selected in the same way as for the Ishii-Zuber model.
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The No solid pressure (the default) disables solid pressure and leaves the collision to be described by a mixture viscosity. This option is appropriate for solid suspension, typically solids suspended in liquids.
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The other options, Gidaspow-Ettehadieh, Gidaspow, Ettehadieh and User defined modulus of elasticity describes particle-particle interaction for dispersed solids, typically solid particles in gas flows. These options should be combined with the Gidaspow model or a small user defined value for .
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For User defined modulus of elasticity enter an expression for the Modulus of elasticity, G (SI unit: N/m2).
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