TwinMesh Features

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Efficient Workflow

Easy and intuitive GUI
Fully automated interface generation between meshes
Fully automated 2D and 3D mesh generation
Export of ready-to-run input files for ANSYS CFD
No compiling of user functions required

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Maximum Flexibility

Import of existing CAD-Data or point-coordinates
Easy geometry scaling (clearance definition, rotor size)
Option for automatic mesh generation for axial clearances
Different mesh export options (2D/3D, one or two meshes for rotors)

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Mesh Control & Mesh Quality

Full user control of mesh size and mesh resolution
Boundary layer generation and local refinements
Advanced mesh smoothing algorithms
Several tools for mesh quality check

How does it work?

Easy Import

In TwinMesh the import of rotor and casing contours is realised as a 2D cross section via IGES format or CSV text files. Casing curves can also be generated in TwinMesh. All these contours can be easily scaled in order to modify e.g. clearance dimensions between rotors and casing. Rotor positions can also be adapted after the import defining axis-positions for the directions X and Y. If required, TwinMesh then automatically generates interfaces between the rotor meshes.

Auto Generation of Hexahedral Meshes

In the next step TwinMesh generates hexahedral meshes for all user defined rotation angles. Using special smoothing algorithms the software takes care of a sufficient gap resolution, smooth changes between small gaps and larger chambers and an homogeneous element distribution.

Easy Export

After a final check of the numerical quality the grids can be exported as 3D model or as 2D model. The export data of TwinMesh contains all required meshes for a transient flow simulation as well as the required routines for the automatic mesh import while running the simulation in ANSYS CFD. Also, a ready-to-run simulation template is exported by TwinMesh, which enables an immediate start of a flow analysis with ANSYS CFD. Using the structured grids from TwinMesh singlephase and multiphase CFD and CHT simulations can be performed in ANSYS CFD.

Implementation of mesh movement in TwinMesh

Rotating positive displacement machines consist of fluid volumes (called chambers) that are connected by gaps. The chambers transport the fluid while the gaps lead to leakage flow (losses). The position and the shape of the chambers and gaps change with time, depending on the position of the rotor(s). For the CFD simulation of the fluid flow with the finite volume method, this change in position and shape has to be accounted for in the meshes that describe and divide the fluid regions.

TwinMesh is a software which pre-generates these numerical meshes of the chambers and gaps for each rotational position and exports the node positions in a set of files. By using structured meshes (typically hexahedral block-structured O-grid meshes), TwinMesh ensures that the topology of the meshes keeps the same for each rotational position, i.e. the node numbers and node connectivities stay the same.

The CFD solver, Ansys CFX or Ansys Fluent, then reads in these mesh files during run-time with special routines provided by TwinMesh and uses them for the deforming mesh approach. The location of each mesh node is updated at the start of each time step, and the CFD solver considers the movement of the mesh nodes as an additional term in the Navier-Stokes equations and further partial differential equations, e.g. for turbulence.

Since the topology of the meshes keeps the same, no interpolation of the solution values is necessary during the transient simulation unlike for the remeshing approach. This reduces the numerical errors significantly and decreases simulation time.

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Fast

TwinMesh provides an automated workflow for structured mesh generation and CFD analysis setup of rotary positive displacement machines

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Reliable

TwinMesh delivers high resolution and high quality numerical grids, avoids interpolation errors and allows the usage of the full range of physics available in ANSYS CFD

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Efficient

Structured grids made with TwinMesh allow for reasonable transient CFD model size while ensuring maximum numerical quality

Works seamless with

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Direct Export to ANSYS CFD

TwinMesh is fully optimized for CFD analysis using leading ANSYS CFD software. It exports mesh data in ANSYS CFD format and ready-to-run input files for ANSYS CFD.

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