Fixed Jump (AMI) - Boundary Condition Description
Fixed Jump (AMI) is a boundary condition that specifies a jump condition - an offset of a field value - between two cyclic (AMI) boundaries. The jump is specified as a fixed value field, applied to the 'owner' patch. The Fixed Jump (AMI) is only available when cyclic conditions are used and is particularly useful in simulations involving rotating or sliding meshes, such as in the study of turbines, gears, or any scenario where two separate mesh regions interact with each other.
- \(\phi_{n}\) - field value on the neighbor patch
- \(\phi_{o}\) - field value on the owner patch
- \(J\) - specified jump (offset) value
Fixed Jump (AMI) - Boundary Condition Understanding Fixed Jump (AMI)
AMI stands for Arbitrary Mesh Interface, and is a method used in CFD simulations to handle the interaction between two distinct mesh regions that may have relative motion. It allows for the transfer of field values (like velocity, pressure, etc.) across non-conforming mesh interfaces.
The Fixed Jump (AMI) is designed to apply a fixed value difference (or 'jump') across such an interface. This is crucial in scenarios where a consistent offset in a field value is expected across the interface due to physical phenomena like pressure drop or temperature gradient.
Fixed Jump (AMI) - Boundary Condition Fixed Jump (AMI) in SimFlow
Once the arbitrary interface is created between two patches in MESH section, the Fixed Jump (AMI) boundary condition can be selected from the drop-down menu.
Jump - field offset between two boundaries
Fixed Jump (AMI) - Boundary Condition Application & Physical Interpretation
The Fixed Jump (AMI) is useful in simulations where two domains are coupled via an interface that acts as a source or sink of the solved variable.
Rotating Machinery (SIMPLE FOAM)
Context: In turbines, fans, or compressors where one part of the mesh is rotating relative to another, Fixed Jump (AMI) can be used to simulate the pressure or temperature jump due to rotation.
Physical meaning: Mimics the constant value of pressure/velocity difference between two rotating regions.
Sliding Interfaces
Context: For simulations involving sliding interfaces, like in gear pumps or sliding valves, this boundary condition can effectively model the changes in field values across the sliding interface.
Physical meaning: Mimics the constant value of pressure/velocity difference between two regions.
| Variable | Owner Patch | Neighbor Patch |
|---|---|---|
Pressure | Fixed Jump (AMI) | cyclicAMI |
Velocity | cyclicAMI | cyclicAMI |
Fixed Jump (AMI) - Boundary Condition Fixed Jump (AMI) - Alternatives
In this section, we propose boundary conditions that are alternative to Fixed Jump (AMI). While they may fulfill similar purposes, they might be better suited for a specific application and provide a better approximation of physical world conditions.
| Boundary Condition | Description |
|---|---|
Works in the same way as Fixed Jump (AMI), but allows defining a time-dependent jump using a spatially uniform value. | |
Standard cyclic coupling with no jump (\(J=0\)). Ensures continuity of the field across the interface. |