Lookup Table¶
Introduction¶
A Lookup Table provides tabulated data that other simulation components or UDFs can query at runtime. Rather than hard-coding piecewise logic or long conditional statements, users can define empirical or vendor-supplied correlations (such as viscosity versus temperature, pump head versus flow rate, or heat-transfer coefficient versus Reynolds number), and let the solver interpolate between the tabulated points as needed.
The table is defined using the context-specific command Edit Lookup Table, which opens a two-column table where you enter the independent variable (x) and the corresponding dependent variable (y). The data pairs in the lookup data do not need to be equally spaced nor do the pairs need to be sorted in any particular order. Any necessary reordering and data resampling will occur at runtime.
The solver evaluates intermediate values using either a cubic spline or a piecewise cubic hermite interpolating polynomial (PCHIP).
In the example below, a non-Newtonian fluid viscosity is defined in a lookup table. This lookup table is evoked in the Kinematic Viscosity UDF, defined within the Custom Fluid rheology type. Intermedia data is interpolated using the PCHIP algorithm.
EXAMPLE
Property Grid¶
General¶
- Interpolation Algorithm
The following are the options for interpolation algorithm.
- PCHIP
The data is interpolated using a Piecewise Cubic Hermite Interpolating Polynomial (PCHIP). The algorithm prevents overshoots by adjusting slopes locally to preserve the data’s shape and monotonicity.
- Cubic Spline
The data is interpolated using a cubic spline. The algorithm prioritizes smoothness but can overshoot data points.
Advanced¶
- Notes
This is an optional text field for recording the units, the source of the data, or other documentation relevant to the table.
Statistics Filter Toolbar¶
Context-Specific Toolbar Options |
Description |
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The Help command launches the M-Star reference documentation in your web browser. |
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The Edit Lookup Table allows you to edit sampled data that other components query at runtime. |
Help
Edit Lookup TableSee also Child Geometry Context Specific Toolbar.
For a full description of each selection on the Context-Specific Toolbar, see Toolbar Selections.