How to access dictionary values from boundary conditions in OpenFOAM

OpenFOAM® offers a standard way to access user-specified constant data by means of dictionaries. However, dictionaries are by default read during the start-up phase of the main code. If a boundary condition requires to access the same information, the value can be looked up from the internal database used by OpenFOAM to store objects. The procedure is quite simple, and I show an example below, in a general case. Let’s assume our solver uses the “transportProperties” dictionary, which contains a subdictionary, called “mySubDict”. This sub-dictionary contains a dimensioned scalar, named “myScalar”. In the BC, you can recover “myScalar” as follows:

// Extract the dictionary from the database
const dictionary& transportProperties = db().lookupObject<IOdictionary>

// Exctract subdictionary from the main dictionary
dictionary mySubDict

// Extracting scalar value
dimensionedScalar myScalar(mySubDict.lookup("myScalar"));

At this point “myScalar” is accessible from inside the code of the boundary condition.

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