volScalarField pressure("p", mesh); pressure = 0;
volVectorField velocity = mesh.readIn this code, "U" is the name of the volVectorField object that stores the velocity field data. The read() method is used to read the field data from a file into the velocity variable. The mag() function is used to calculate the magnitude of the velocity at each point in the mesh, which is then stored in a new volScalarField object called velocityMag.("U"); volScalarField velocityMag = mag(velocity);