Defining an Interpolation Function Using an Excel® File
You will now import data stored in a workbook to define an interpolation function in the model. The function defines the temperature dependency of the heat transfer coefficient between the busbar and the surrounding air.
1
In the Home toolbar, click Functions  in the Definitions group. Under the Local section, select Interpolation . On Linux and Mac, the Home toolbar refers to the specific set of controls near the top of the Desktop.
2
In the Settings window, under the Definition section, in the Function name text field, enter htc.
3
Now click Load from File .
4
In the Load from File dialog, select the Microsoft Excel Workbook (*.xlsx) file type, and navigate to the COMSOL installation directory. In the folder applications/LiveLink_for_Excel/Tutorials, select the file busbar_llexcel_data.xlsx, then click Open.
The interpolation data is stored in the workbook in a worksheet named htc(T). The temperature values and the corresponding heat transfer coefficient values are defined in two columns, as can be seen in the figure to the right.
5
In the Settings window for Interpolation enter htc(T) in the Sheet text field.
6
In the Range field enter A2.
7
To import the data, click Load.
The interpolation table is filled using the data stored in the Excel file.
8
Locate the section, Interpolation and Extrapolation. In the Interpolation list, select Piecewise cubic.
9
Locate the section, Units. In the Function text field enter W/(m^2*K). In the Arguments text field enter K.
 
 
10
To display the interpolation curve, click Plot.
Now continue with changing the model settings to use the newly defined function for the heat transfer coefficient in the heat flux boundary condition.
11
In the Model Builder, under the Component 1 node, expand the Heat Transfer in Solids nodes and then click Heat Flux 1.
12
In the Settings window for Heat Flux replace the expression in the Heat transfer coefficient text field with htc(T).