.Modelica.Fluid.Pipes.DynamicPipe .Modelica.Fluid.Pipes.DynamicPipeModel of a straight pipe with distributed mass, energy and momentum balances. It provides the complete balance equations for one-dimensional fluid flow as formulated in UsersGuide.ComponentDefinition.BalanceEquations.
This generic model offers a large number of combinations of possible parameter settings. In order to reduce model complexity, consider defining and/or using a tailored model for the application at hand, such as HeatExchanger.
DynamicPipe treats the partial differential equations with the finite volume method and a staggered grid scheme for momentum balances. The pipe is split into nNodes equally spaced segments along the flow path. The default value is nNodes=2. This results in two lumped mass and energy balances and one lumped momentum balance across the dynamic pipe.
Note that this generally leads to high-index DAEs for pressure
states if dynamic pipes are directly connected to each other, or
generally to models with storage exposing a thermodynamic state
through the port. This may not be valid if the dynamic pipe is
connected to a model with non-differentiable pressure, like a
Sources.Boundary_pT with prescribed jumping pressure. The
modelStructure can be configured as
appropriate in such situations, in order to place a momentum
balance between a pressure state of the pipe and a
non-differentiable boundary condition.
The default modelStructure is
av_vb (see Advanced tab). The simplest possible
alternative symmetric configuration, avoiding potential high-index
DAEs at the cost of the potential introduction of nonlinear
equation systems, is obtained with the setting nNodes=1,
modelStructure=a_v_b. Depending on the configured model
structure, the first and the last pipe segment, or the flow path
length of the first and the last momentum balance, are of half
size. See the documentation of the base class Pipes.BaseClasses.PartialTwoPortFlow,
also covering asymmetric configurations.
The HeatTransfer component
specifies the source term Qb_flows of the energy
balance. The default component uses a constant coefficient for the
heat transfer between the bulk flow and the segment boundaries
exposed through the heatPorts. The
HeatTransfer model is replaceable and can be exchanged
with any model extended from
BaseClasses.HeatTransfer.PartialFlowHeatTransfer.
The intended use is for complex networks of pipes and other flow devices, like valves. See, e.g.,
| Name | Description |
|---|---|
 HeatTransfer |