[GeoMechanicsApplication] Phreatic error with discontinuous geometry

[EleniSmyrniou]

As a user, I would like to be able to apply a multiple-point phreatic line, such that I can model water pressure fields.

Description

When multiple phreatic lines are assigned to a surface it seems that the first point in the left is always extrapolated to the right. As it can be seen in the figures bellow.

Acceptance Criteria

[EleniSmyrniou]

The problem can be found in apply_scalar_constrain_table_process.py in function CalculatePressure.
In this case when the node is outside of the phreatic line the pressure gets extrapolated. This makes assigning different phreatic lines in the same surface order dependent

` double CalculatePressure(const Node<3> &rNode, const array_1d<double, 2> &y) const
{
double height = 0.0;
if (rNode.Coordinates()[mHorizontalDirection] >= mMinHorizontalCoordinate && rNode.Coordinates()[mHorizontalDirection] <= mMaxHorizontalCoordinate) {
height = mSlope * (rNode.Coordinates()[mHorizontalDirection] - mFirstReferenceCoordinate[mHorizontalDirection]) + y[0];

    } else if (rNode.Coordinates()[mHorizontalDirection] < mMinHorizontalCoordinate) {
        height = mSlope * (mMinHorizontalCoordinate - mFirstReferenceCoordinate[mHorizontalDirection]) + y[0];

    } else if (rNode.Coordinates()[mHorizontalDirection] > mMaxHorizontalCoordinate) {
        height = mSlope * (mMaxHorizontalCoordinate - mFirstReferenceCoordinate[mHorizontalDirection]) + y[0];
    }

    const double distance = height - rNode.Coordinates()[mGravityDirection];
    const double pressure = - PORE_PRESSURE_SIGN_FACTOR * mSpecificWeight * distance;
    return pressure;
}`

[mcgicjn2]

Fixed for constant pressure

[mcgicjn2]

Also added phreatic multi line table process .... i.e. varies in time

[mcgicjn2]

The PR was closed so that @WPK4FEM and @avdg81 can complete there changes to the underlying functionalities before reimplementation.