User manual

Dymola 2015 FD01 Release Notes 49
• Both the receiver and accumulator can be initialized using a liquid level.
• Adding specific interfaces to the heat exchanger models increased replaceability and
reusability of the models in a system context.
• The default air model is replaced with one, which is better suited for challenging
steady-state initialization. Basically the same assumptions apply except that the new
model neglects the liquid volume in case liquid water droplets are transported by the
air stream and assumes that they do not influence the specific heat capacity. The
previously used model can still be selected from a drop-down list.
• The medium model for CO2 has an improved robustness around the critical point.
Existing models can be converted to this version using the supplied conversion script.
3.6.17 Vehicle Dynamics Library
A new version 2.0 of the Vehicle Dynamics Library is available.
New features
Pacejka '94 Tire Contact Force Model
Support for the Pacejka '94 'Magic Formula' contact force model has been added. The
Pacejka '94 contact force model provides the benefit that it requires fewer coefficients than
newer models; is more commonly used than the Pacejka '02 model; and is used in many
other vehicle dynamics software products. By supporting this contact force model natively
in VDL, the Pacejka '94 tire coefficients can be shared between VDL and other simulation
tools.
Suspension Wheel Test Rig
A new live tire suspension test rig has been added that allows the application of external
forces and torques at either the contact patch or wheel center/hub. In physical kinematics
and compliance tests, it is quite common to have a wheel and tire mounted on the
suspension. It is the intent of this new rig to be able to better mimic the actual physical tests.