Altair AcuSolve 2021.2 Release Notes

Porous Media Physical Velocity

Filter media and other flow-through components are often modeled in larger domains as simple porous media with a known pressure-drop-to-velocity ratio. While the intricacies of the flow through the tortuous paths around fibers, tube bundles, and other solid obstructions is sometimes ignored, you will occasionally be interested in a more physical representation of the flow within these components. Flow in the normal direction through a porous medium, as viewed by an observer, is referred to as the Superficial Velocity; or the relative decrease in velocity in the original flow direction that corresponds to the assigned pressure drop. As the flow travels through the physical medium, however, it has the potential to accelerate in directions orthogonal to the original incoming flow direction. These more physical results using Physical Velocity are now available for output from AcuSolve.

Topology Optimization

AcuSolve integrated optimization capability grows yet again with the addition of topology optimization. Find your optimum shape by simply defining inlets, outlets, and the allowable space in which the solver can work. AcuSolve’s gradient-based topology optimization method will quickly and efficiently find the path of least resistance to deliver your fluid with minimal effort.

EDEM/AcuSolve: Non-spherical Particle Lift Models

Speed, robustness, and accuracy, three qualities that AcuSolve has enjoyed for years. As AcuSolve integrates further with Altair EDEM, accurate representation of individual particles within the fluid domain becomes even more important. To support this AcuSolve has added two new lift models for non-spherical particles. The first model, nonspherical_lift, is the aerodynamic lift force arising from the particle incidence angle. The second model, Saffman_Magnus_nonspherical_lift, incorporates the lift effect of shear flow and rotation in addition to the aerodynamic lift force due to particle incidence angle.

EDEM/AcuSolve: Non-spherical Particle Torque Model

As AcuSolve/EDEM coupling continues to evolve and grow to support more and more physically accurate scenarios the particles modeled become less and less standard, or spherical. As particles in an airstream become less spherical the impact of torque on the particle due to the surrounding airflow becomes greater. You can now accurately account for the torque experienced by high aspect ratio, low sphericity particles. Methods for modeling torque due to pitching, torque due to rotation, and torque due to the combination of pitching and rotation are all now available.

EDEM/AcuSolve: Scaling factor for Lift and Drag

Particle counts in large industrial models can occasionally become quite large. Modeling each individual particle in these scenarios can also become quite expensive. To alleviate the large computational cost while still running large industrial models AcuSolve/EDEM coupling now allows for scaling of lift and drag forces. With this capability single particles in EDEM can now represent a collection of many smaller physical particles. Modeling the collection of many physical particles directly as a single particle in EDEM with equivalent mass and volume typically results in larger lift and drag forces than desired. The scaling factor mitigates this condition.

EDEM/AcuSolve: Particle Mass Transfer

The purpose of coupling solvers is to include the physics modeling that each does best. One of AcuSolve’s many strengths is in the accurate modeling of heat transfer and extending its capability to include mass transfer at a particle boundary is a natural progression. With AcuSolve 2021.2 you will be able to model the accumulation of spray on particles in an EDEM simulation and the evaporation of the water content of the accumulated spray during an AcuSolve/EDEM coupled simulation.

Negative Density reported in Log file

The AcuSolve Log file now includes a short list of coordinate locations indicating points where the solver returns negative density values. This is typically encountered when variable density models are used, and the overall model setup is not quite synchronized. The location information is helpful to give you an idea of where to look in the model to correct boundary or operating conditions. If the number of locations is greater than five, more information about the total number of points where density is negative is also reported.

Utility programs

• AcuMakeDLL, used to compile and link user-defined functions on Windows, will automatically search for Enterprise, Professional, and Community versions of MicroSoft Visual Studio. AcuSolve supports versions of Visual Studio up through version 2019.
• AcuCpOutFiles, a script which copies the minimum number of files allowing you to process output data, is now available on Windows and Linux platforms.
• AcuCpRstFiles, a script which copies the minimum number of files allowing you to restart from an earlier simulation, is now available on Windows and Linux platforms.

Tutorial Additions

The following new tutorials have been added for the HyperWorks CFD interface:

• ACU-T: 2300: Atmospheric Boundary Layer Problem – Flow Over Building
• ACU-T: 3110: Exhaust Manifold Conjugate Heat Transfer - CFD Data Mapping using acuOptiStruct
• ACU-T: 4002: Sloshing of Water in a Tank
• ACU-T: 5403: Piezoelectric Flow Energy Harvester: A Fluid-Structure Interaction
• ACU-T: 6105: Single Particle Sedimentation – Effect of Lift and Torque
• ACU-T: 6106: AcuSolve - EDEM Bidirectional Coupling with Mass Transfer
• ACU-T: 6501: Flow Through Porous Medium with Physical Velocity

Validation Additions

The following six validation cases have been updated to the HyperWorks CFD platform:

1. Turbulent Flow Over a Backward-Facing Step
2. Turbulent Flow with Separation in an Asymmetric Diffuser
3. Turbulent Flow Past a Convex Curve in a Channel
4. Turbulent Flow Through a 180 Degree Curved Channel
5. Turbulent Mixing Layers in an Open Channel
6. Laminar to Turbulent Transition Over an Airfoil

Documentation Additions

• In the Command Reference Manual, the default value of the outflow_type parameter under SIMPLE_BOUNDARY_CONDITION was corrected to be auto_pressure instead of pressure.
• In the Command Reference Manual, clarification regarding the usage of the from_directory option of the RESTART command has been added.
• In the Command Reference Manual, the default value of 273.15 for convective heat reference temperature has been updated.
• In the Programs Reference Manual, documentation has been added for the AcuGetNodeSubset script command options.
• In the Programs Reference Manual, the description for HTC Method 2 of AcuTherm has been improved.
• In the User-Defined Functions Manual, Global Routines section, the function name of udfGetMmoRgdJac() has been corrected.

The following known issues will be addressed in a future release as we continuously improve performance of the software:

• Legacy support for AcuConsole GUI is not supported on Linux versions of RHEL/CentOS higher than 7.5 and SLES versions higher than 15.
• Users on platforms later than RHEL/CentOS 7.5 or SLES 15 are encouraged to use the Altair Compute Console interface for launching simulations.
• AcuSolve users using the HyperWorks CFD user interface should update both solver and GUI to version 2021.2 together.

• Thermal shell creation on floating, non-manifold surfaces is now working correctly.
• An issue with thermal shell definition which prevented post-processing of data has been corrected.
• An error with the AcuTrans “-dir” option, to specify a working directory other than the current directory, has been fixed.
• An issue where parallel jobs using Intel MPI were being overloaded on a single host has been corrected.
• An error with AcuPlotData correctly plotting fft data has been resolved.
• ACU-T: 4001 and 4002: Missing Steps have been added to assign material properties.
• ACU-T: 4003: Steps to define nodal initial conditions have been added.
• ACU-T: 4100: Text has been added indicating that the carrier field must be the heavier fluid.
• ACU-T: 5000: Steps demonstrating the creation of monitoring surfaces have been added.
• ACU-T: 5201: Steps to launch the coupling via Altair Compute Console have been added.
• ACU-T: 6104: A screen shot of a table of particle sizes has been updated.
• ACU-T: 6010 was renumbered to ACU-T: 6500 for v2021.1.