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    SimScale DocumentationKnowledge BaseError: Table is Not Rectangular

    Error: Table is Not Rectangular

    Created On
    bysblock

    Error

    Table is not rectangular. Product of the table dimesion found (3×3) is not equal to the flattend, original table data size (3).

    What Happened?

    The “Table is not rectangular” error message indicates an invalid density or enthalpy table when defining the material properties for a real gas in SimScale.

    What Could Be the Possible Reason?

    The Subsonic solver, when using the real gas models for a compressible analysis, requires a user-defined table of the density and enthalpy curves. When setting up these curves, the user must ensure that the same number of data points are provided for each data point in a column. This means when setting up a temperature data point with multiple pressure data points, each temperature data point should receive the same pressure data points.

    Vice versa, when setting up a pressure data point with multiple temperature data points, each pressure data point should receive the same temperature data points.

    Figure 1 shows an example of an invalid setup for a density curve. It can be seen that for three different temperature data points, 0, 15, and 30 \(°C\), the pressure and density are defined. However, for 0 and 30 \(°C\) two pressure points are defined, whilst for 15 \(°C\) only a single pressure point is defined. So the pressure data points for each temperature data point are not equivalent, i.e. there is no definite pattern.

    Table set up incorrectly with nor pattern in the table is not rectangular error message
    Figure 1: Invalid table setup, with an additional pressure point missing for the 15 \(°C\) temperature.

    What Can I Do Now?

    In order to resolve this error, define the same data points for each individual data point. Figure 2 shows the corrected setup for the table from Figure 1. The missing data point for 15 \(°C\) has been added so that each temperature data point has the same pressure data points.

    Table set up correctly with equal number of pressure and temperature points in the table is not rectangular error message
    Figure 2: Corrected table setup, with added pressure point for the 15 \(°C)\ temperature.

    Further example

    Below is an example of invalid table inputs and solutions.

    Invalid Matching Pairs

    Another issue can be that amount of data points is valid, but the data points are not matching. For example, Figure 3 shows two data points for temperature each point having a corresponding pressure definition. However, the two data points for pressure are not matching for every temperature point.

    Table set up incorrectly with no Pairs
    Figure 3: Invalid table set up, with unmatching pairs of temperature and pressure data points.

    Hence, ensure that each pressure point has the same amount of temperature data points to resolve this issue.

    Missing temperature points were added and the valid setup can be seen in Figure 4.

    Table set up correctly with pairs
    Figure 4: Corrected table setup, with the addition of temperature points for the equivalent pressure points to match the pairs.

    Valid Scenarios

    Scenarios with:

  • Three temperature points and a single pressure point;
  • Two temperature points and two pressure points

    • are valid patterns as well.

    Important Information

    If none of the above suggestions solved your problem, then please post the issue on our forum or contact us.

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    Last updated: May 10th, 2023

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