# DensityIntegration¶

Use this post-process to integrate a computed tensor field or an user-defined expression over selected physical domains. It is required that the integrand, e.g., the tensor field is a scalar volume density. For example, it is possible to integrate over an energy density field.

It is possible to compute several integral values in one post-process call. For example, a JCM fieldbag may contain several fields of the desired density type. Then all integrals for the multiple fields are computed, and stored in the output file separately.

When computing mutual overlap integrals by an expression involving the fields of two fieldbags, the number of integrals will be the product of the numbers of fields in the two fieldbags.

The output is stored in a JCM table file with the following columns:

Column 1:

**DomainId**The integral values are computed domain-wise. The

`DomainId`

refers to the physical domain as specified in the layout.Columns 2-…:

**<Quantity>_<Suffix>**These columns store the actual integral values.

`<Quantity>`

stands for the name of the computed value.`<Suffix>`

is an additional index needed to label separate integral values. For example, a JCM fieldbag may contain several fields of the desired density type. Then`<Suffix>`

is the field index. When computing mutual overlap integrals the`<Suffix>`

is a pair of field indices.