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Viscosity Tab

The viscosity of material is set on this tab.

It is in the [Edit Material Property] dialog box. See [How to Set Body Attribute/Material Property].

It is required for the fluid analysis.

This tab will be enabled if "Fluid" is selected on the [Solid/Fluid] tab of the material property in the fluid analysis [Bernoulli] or fluid-thermal coupled analysis [Pascal/Watt].
For the turbulent flow analysis, only Newtonian fluid is selectable.
Power law model, Carreau model, and share rate-viscosity (table input) are supported for non-Newtonian fluid.

Setting Item	Notes
Newtonian Fluid	[Viscosity] The significand is a real number greater than 0. [Temperature Dependency] Sets either No or Yes. If Yes is set, click . The [Temperature-Viscosity] table will show up. Enter the data here. Click the Graph button to see the graph of entered data. At least two data for [Temperature] and [Viscosity] are required respectively to draw a graph.
Power Law	Calculates the coefficient of viscosity by the equation in the image above (S is shear rate [/s]). Represented by n as follows: Newtonian fluids (n=1); Dilatant fluids such, as starch suspensions (n>1); and pseudoplastic fluids, such as liquid resin in injection molding (n<1). The n and A are parameters, and μ0 is the lower limit for Dilatant fluids or the upper limit for pseudo thermoplastic fluids. Improper parameters may cause abnormal values for pressure or flow velocity. Check the parameters. Note that the value of μ0 is just recommended. During parameter fitting, this range may be exceeded. The units of parameters are μ [Pa・s], A[ Pa・s^n], and S [/s].
Carreau model (for pseudoplastic fluids)	Calculates the coefficient of viscosity by the equation in the image above (S is shear rate [/s]). Shear strain rates S→0 results in μ0 and S→∞ results in μ∞, which indicate the upper limit and lower limit of viscosity, respectively. The n and A are parameters. When n=1, Newtonian fluids are represented. The units of parameters are μ [Pa・s], A[s], and S [/s].
Shear Rate-Viscosity (Table Input)	・Shear Rate-Viscosity Table Input to Curve Fit Enter the measurement data from a rotational viscosimeter (rheometer) and click the curve fitting button. Then, the parameters of the power law or Carreau model can be obtained through fitting. By default, the data is fitted using a logarithmic scale. At least three data must be entered. ・Curve Fitting Result to Apply Result The results obtained from curve fitting are displayed in the window. [Apply results to power law] Button: The results obtained from curve fitting are automatically applied to the parameters of the power law viscosity model. [Apply results to Carreau model] Button: The results obtained from curve fitting are automatically applied to the parameters of the Carreau viscosity model. [Recalculation] Button: Parameters can be recalculated using the initial values filled in the fields for [Initial Parameters for Power Law Model] and [Initial Parameters for Carreau Model]. Recalculating with properly specified initial values can enhance the accuracy of curve fitting. Specify the initial value for each parameter such that the residual norm is minimized. For Dilatant fluids (power law parameter n > 1), parameters are fitted only for the power law model. Only the results of power law can be applied. For pseudoplastic fluids (power law parameter n <1), since parameters are fitted to both power law and Carreau models, the viscosity model to which fitting results will be applied is selectable. The model with a smaller residual norm is recommended. Selecting [Linear Fitting] changes the curve fitting method from logarithmic fitting to linear fitting. If logarithmic fitting does not give the intended results, selecting [Linear Fitting] to recalculate can significantly improve the results. If the measurement data from a rotational viscosimeter (Rheometer) is used as it is, logarithmic fitting is recommended. If data is thinned out at equal intervals, linear fitting is recommended. For pseudoplastic fluids, the fitting result of μ0 for power law is set to the value of μ0 for Carreau model. Change it as needed.