{"id":461426,"date":"2026-07-16T17:59:51","date_gmt":"2026-07-16T17:59:51","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/maxwell-3d-ac-magnetic-impedance-boundary-anisotropic-permeability-winding\/"},"modified":"2026-07-16T17:59:51","modified_gmt":"2026-07-16T17:59:51","slug":"maxwell-3d-ac-magnetic-impedance-boundary-anisotropic-permeability-winding","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/maxwell-3d-ac-magnetic-impedance-boundary-anisotropic-permeability-winding\/","title":{"rendered":"Maxwell 3D AC Magnetic: impedance boundary + anisotropic permeability + winding"},"content":{"rendered":"

<p>Hello,<\/p><p>I am modeling stray losses in a power transformer under zero-sequence (homopolar)<br>excitation in Maxwell 3D, AC Magnetic (eddy current) solver, AEDT 2026 R1. The model<br>requires, at the same time:<\/p><p>1. Tank walls represented with the nonlinear impedance boundary condition (NLSIBC),<br>   since meshing the solid steel at 50 Hz skin depth is not practical.<br>2. Current-driven windings (winding setup with coil terminals), with per-segment<br>   excitation.<br>3. Laminated GO magnetic wall shunts, whose physically correct representation is an<br>   anisotropic nonlinear permeability (B-H curves in the lamination plane, collapsed<br>   permeability in the stacking direction).<\/p><p>The Maxwell help topic “Impedance Boundary” states that when a project includes an<br>impedance boundary condition, a material with anisotropic permeability and a winding<br>at the same time, it cannot be solved by the eddy current solver nor the 3D transient<br>solver. I have tested this systematically on 2026 R1 with a minimal synthetic model<br>(copper ring + coil terminal + stranded current winding; steel_1008 plate with<br>nonlinear impedance boundary, solve inside off; one test block whose material is the<br>only thing that changes):<\/p><p>- Block with **linear** anisotropic permeability (constant tensor 5000 \/ 5000 \/ 25):<br>  **solves normally**.<br>- Block with **nonlinear** anisotropic permeability (B-H curves per tensor component,<br>  different curve in the stacking direction): **solver aborts** with:<\/p><p>  > Maxwell 3D eddy current solver does not support the project when the following<br>  > conditions are applied at the same time in one design: 1. Impedance boundary<br>  > condition 2. Anisotropic permeability material 3. Winding setup<\/p><p>- Block with an anisotropic property type but **three identical B-H curves**<br>  (isotropic de facto): **also aborts** with the same message, so the check appears<br>  to be triggered by the declared property type (AnisoProperty + nonlinear), not by<br>  the actual values.<\/p><p>Questions:<\/p><p>1. Can Ansys confirm that the restriction applies only to **nonlinear** anisotropic<br>   permeability, and that linear anisotropic tensors are fully supported in this<br>   combination? The help topic does not make this distinction, and it matters for<br>   choosing a modeling strategy. If linear anisotropy is supported, is the solution<br>   accuracy guaranteed, or does the solver silently degrade anything?<br>2. Is there a roadmap to remove this limitation in an upcoming release?<br>3. What is the recommended workflow for laminated magnetic shunts when the tank must<br>   stay as NLSIBC and the excitation must be a winding? The options I see are:<br>   (a) linear anisotropic tensor for the shunt (no saturation), optionally iterating<br>   the in-plane permeability to a secant value at the operating point;<br>   (b) isotropic nonlinear B-H for the shunt plus a discrete air gap between shunt<br>   and wall sized as g = t_shunt · (1 − F) to restore the missing through-thickness<br>   reluctance of the stack;<br>   (c) replacing the winding with imposed current excitations, which does solve with<br>   anisotropy, but loses the winding\/circuit coupling.<br>   Is any of these the intended path, or is there a better supported approach<br>   (e.g. lamination composition with stacking factor — does the lamination model<br>   trip the same check)?<br>4. Minor related issue: is the restriction expected to behave identically in 3D<br>   transient with the nonlinear impedance boundary introduced in 2021 R2?<\/p><p>Setup details: AEDT 2026 R1, Maxwell 3D, AC Magnetic, 50 Hz, adaptive setup. The<br>minimal reproduction project is a few MB and I can attach it if useful.<\/p><p>Thank you.<\/p><\/p>\n","protected":false},"template":"","class_list":["post-461426","topic","type-topic","status-publish","hentry"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t