Integration Settings for a Derived Value
The settings in the Integration Settings section are available for average, integration, and standard deviation features added under Derived Values and Evaluation Group nodes.
Select a Method: Auto (the default), Integration, or Summation over nodes.
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Auto — the default method, which computes the integral for fields by numerical integration and for reaction forces by summation. Predefined quantities for reaction forces use summation instead of integration. Also, if an expression is specified for the integrand using the reacf operator, the automatic setting chooses the summation method.
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 Integration — the standard numerical integration method (quadrature).
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 Summation over nodes — a summation method is useful for calculating reaction forces. The summation method finds all nodes on the boundary, evaluates the expression in the nodes, and sums up the values. Reaction force variables are predefined in the structural mechanics interfaces.
When calculating the standard deviation of an expression over a set of domains, boundaries, or edges, the standard numerical integration method is always used.
The COMSOL Multiphysics software determines an appropriate Integration order for the expression when you use integration. To change the order, select the checkbox and enter an integer (0 or larger; default: 4). The COMSOL Multiphysics software performs the integration elementwise using numeric quadrature of the selected order.
2D Axisymmetric Models
For 2D axisymmetric models, Volume Integration and Surface Integration are available and active by default. COMSOL Multiphysics multiplies the expression (integrand) with 2*pi*r prior to integration to compute the corresponding volume or surface integral if you do the next step.
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For Surface Average, Surface Integration, and Surface Standard Deviation the Compute volume integral checkbox is selected by default.
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For Line Average, Line Integration, and Line Standard Deviation the Compute surface integral checkbox is selected by default.
Reaction force variables in axisymmetric models include the 2πr factor, so summation over them always gives you the revolved surface force or volume force.