The syringePressure is a boundary condition that provides a pressure condition, obtained from a zero-D model of the cylinder of a syringe.

The syringe cylinder is defined by its initial volume, piston area and velocity profile specified by regions of constant acceleration, speed and deceleration. The gas in the cylinder is described by its initial pressure and compressibility which is assumed constant, i.e. isothermal expansion/compression.


The condition requires entries in both the boundary and field files.

Boundary file

    type            patch;

Field file

    // Mandatory entries
    type            syringePressure;
    Ap              <scalar>;
    Sp              <scalar>;
    VsI             <scalar>;
    tas             <scalar>;
    tae             <scalar>;
    tds             <scalar>;
    tde             <scalar>;
    psI             <scalar>;
    psi             <scalar>;
    ams             <scalar>;

    // Optional entries
    phi             <word>;

    // Inherited entries


Property Description Type Required Default
type Type name: syringePressure word yes -
Ap Syringe piston area [m^2] scalar yes -
Sp Syringe piston speed [m/s] scalar yes -
VsI Initial syringe volume [m^3] scalar yes -
tas Start of piston acceleration [s] scalar yes -
tae End of piston acceleration [s] scalar yes -
tds Start of piston deceleration [s] scalar yes -
tde End of piston deceleration [s] scalar yes -
psI Initial syringe pressure [Pa] scalar yes -
psi Gas compressibility [m^2/s^2] scalar yes -
ams Added (or removed) gas mass [kg] scalar yes -
phi Name of flux field word no phi

The inherited entries are elaborated in:

Further information


  • N/A

Source code:



  • Introduced in version 1.5