March 2026 critical fixes

Bug 118408: Incorrect temperature results are obtained for an orbital heating model run in parallel with the deterministic calculation method when a partial orbit’s start time coincides with the previous partial orbit’s end time

A defect in the thermal solver was resolved where incorrect temperature results were produced in orbital heating simulations using the deterministic calculation method when running in parallel. This issue occurred when the start time of a partial orbit coincided with the end time of the preceding partial orbit. Serial runs were not affected.

User Story 121406: Update the convecting area used in convective heat flux calculations when an internal line between two plane stress meshes is selected in a thermal coupling

The thermal solver was updated to use the correct convecting area for convective heat flux calculations when an internal line between two plane stress meshes is selected in a thermal coupling. Previously, this could result in inaccurate convective heat flux results.

This correction applies differently depending on the thermal coupling type:

• For heat transfer coefficient or conductive gap thermal couplings, the convecting area was corrected for the secondary region only.
• For total conductance or total resistance thermal couplings, the convecting area was corrected for both the primary and secondary regions.

User Story 121708: Retire WARNING 4099 and introduce FATAL 9081 in the DATACH module when a plane stress element edge is included in an enclosure radiation request without using the Monte Carlo or GPU computed ray tracing calculation method

Fixed version: 2606.0

The DATACH module was updated to retire WARNING 4099 and introduce FATAL 9081 to properly support enclosure radiation requests involving plane stress element edges.

Previously, WARNING 4099 notified users when an enclosure radiation request included a shared edge between plane stress elements, as this condition could lead to invalid analyses.

With this solver update, WARNING 4099 was retired and replaced by FATAL 9081, which is issued when the edge of a plane stress element is included in an enclosure radiation request using unsupported calculation methods, specifically Hemicube rendering, deterministic, and GPU computed view factors. Only Monte Carlo and GPU computed ray tracing calculation methods are supported for such cases.

User Story 122111: Ensure that automatically generated coating elements are assigned to plane stress elements with the largest thickness and that coating surface normals are oriented outward when boundary conditions are applied to internal lines between plane stress meshes

Fixed version: 2606.0

The thermal solver has been enhanced to ensure consistent application of automatic generation of 1D coating elements when boundary conditions are defined on internal lines between adjacent plane stress elements.

With this solver update:

• Coating elements are now consistently assigned to the plane stress element with greater thickness.
• Coating surface normals are oriented outward.

Previously, coating elements could be inconsistently assigned to either side of the interface, which in some cases led to inaccurate thermal results.

This fix may lead to changes in simulation results when boundary conditions are applied to internal lines between plane stress elements. The extent of the impact depends on the boundary condition:

• For radiation, changing the coating side may modify computed view factors, affecting radiative heat flux and, consequently, temperatures.
• For temperature combined with another boundary condition, changing the coating side may influence boundary condition precedence, which can in turn affect temperature results.

Bug 122740: Performance regression observed when running TMG modules via MPI on hybrid CPU systems with Hyper-Threading enabled in version 2512, affecting Windows only

Fixed version: 2512.5

A performance regression was resolved that affected parallel-capable TMG modules when running via MPI on hybrid CPU systems with Hyper-Threading enabled in version 2512 on Windows, resulting in increased run-times for affected simulations.

The regression was introduced by changes intended to address issues seen with Intel MPI 2021.15.1 on Linux systems using hybrid CPU architectures (E-core/P-core) with Hyper-Threading enabled. These changes were inadvertently applied to Windows, where they negatively impacted performance.

This issue has been corrected, restoring expected performance for parallel TMG modules on Windows.