{"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>&lt;p&gt;Hello,&lt;\/p&gt;&lt;p&gt;I am modeling stray losses in a power transformer under zero-sequence (homopolar)&lt;br&gt;excitation in Maxwell 3D, AC Magnetic (eddy current) solver, AEDT 2026 R1. The model&lt;br&gt;requires, at the same time:&lt;\/p&gt;&lt;p&gt;1. Tank walls represented with the nonlinear impedance boundary condition (NLSIBC),&lt;br&gt;&nbsp; &nbsp;since meshing the solid steel at 50 Hz skin depth is not practical.&lt;br&gt;2. Current-driven windings (winding setup with coil terminals), with per-segment&lt;br&gt;&nbsp; &nbsp;excitation.&lt;br&gt;3. Laminated GO magnetic wall shunts, whose physically correct representation is an&lt;br&gt;&nbsp; &nbsp;anisotropic nonlinear permeability (B-H curves in the lamination plane, collapsed&lt;br&gt;&nbsp; &nbsp;permeability in the stacking direction).&lt;\/p&gt;&lt;p&gt;The Maxwell help topic &#8220;Impedance Boundary&#8221; states that when a project includes an&lt;br&gt;impedance boundary condition, a material with anisotropic permeability and a winding&lt;br&gt;at the same time, it cannot be solved by the eddy current solver nor the 3D transient&lt;br&gt;solver. I have tested this systematically on 2026 R1 with a minimal synthetic model&lt;br&gt;(copper ring + coil terminal + stranded current winding; steel_1008 plate with&lt;br&gt;nonlinear impedance boundary, solve inside off; one test block whose material is the&lt;br&gt;only thing that changes):&lt;\/p&gt;&lt;p&gt;- Block with **linear** anisotropic permeability (constant tensor 5000 \/ 5000 \/ 25):&lt;br&gt;&nbsp; **solves normally**.&lt;br&gt;- Block with **nonlinear** anisotropic permeability (B-H curves per tensor component,&lt;br&gt;&nbsp; different curve in the stacking direction): **solver aborts** with:&lt;\/p&gt;&lt;p&gt;&nbsp; &gt; Maxwell 3D eddy current solver does not support the project when the following&lt;br&gt;&nbsp; &gt; conditions are applied at the same time in one design: 1. Impedance boundary&lt;br&gt;&nbsp; &gt; condition 2. Anisotropic permeability material 3. Winding setup&lt;\/p&gt;&lt;p&gt;- Block with an anisotropic property type but **three identical B-H curves**&lt;br&gt;&nbsp; (isotropic de facto): **also aborts** with the same message, so the check appears&lt;br&gt;&nbsp; to be triggered by the declared property type (AnisoProperty + nonlinear), not by&lt;br&gt;&nbsp; the actual values.&lt;\/p&gt;&lt;p&gt;Questions:&lt;\/p&gt;&lt;p&gt;1. Can Ansys confirm that the restriction applies only to **nonlinear** anisotropic&lt;br&gt;&nbsp; &nbsp;permeability, and that linear anisotropic tensors are fully supported in this&lt;br&gt;&nbsp; &nbsp;combination? The help topic does not make this distinction, and it matters for&lt;br&gt;&nbsp; &nbsp;choosing a modeling strategy. If linear anisotropy is supported, is the solution&lt;br&gt;&nbsp; &nbsp;accuracy guaranteed, or does the solver silently degrade anything?&lt;br&gt;2. Is there a roadmap to remove this limitation in an upcoming release?&lt;br&gt;3. What is the recommended workflow for laminated magnetic shunts when the tank must&lt;br&gt;&nbsp; &nbsp;stay as NLSIBC and the excitation must be a winding? The options I see are:&lt;br&gt;&nbsp; &nbsp;(a) linear anisotropic tensor for the shunt (no saturation), optionally iterating&lt;br&gt;&nbsp; &nbsp;the in-plane permeability to a secant value at the operating point;&lt;br&gt;&nbsp; &nbsp;(b) isotropic nonlinear B-H for the shunt plus a discrete air gap between shunt&lt;br&gt;&nbsp; &nbsp;and wall sized as g = t_shunt &middot; (1 &minus; F) to restore the missing through-thickness&lt;br&gt;&nbsp; &nbsp;reluctance of the stack;&lt;br&gt;&nbsp; &nbsp;(c) replacing the winding with imposed current excitations, which does solve with&lt;br&gt;&nbsp; &nbsp;anisotropy, but loses the winding\/circuit coupling.&lt;br&gt;&nbsp; &nbsp;Is any of these the intended path, or is there a better supported approach&lt;br&gt;&nbsp; &nbsp;(e.g. lamination composition with stacking factor &mdash; does the lamination model&lt;br&gt;&nbsp; &nbsp;trip the same check)?&lt;br&gt;4. Minor related issue: is the restriction expected to behave identically in 3D&lt;br&gt;&nbsp; &nbsp;transient with the nonlinear impedance boundary introduced in 2021 R2?&lt;\/p&gt;&lt;p&gt;Setup details: AEDT 2026 R1, Maxwell 3D, AC Magnetic, 50 Hz, adaptive setup. The&lt;br&gt;minimal reproduction project is a few MB and I can attach it if useful.&lt;\/p&gt;&lt;p&gt;Thank you.&lt;\/p&gt;<\/p>\n","protected":false},"template":"","class_list":["post-461426","topic","type-topic","status-publish","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_forum_id":["27793"],"_bbp_topic_id":["461426"],"_bbp_author_ip":["83.35.117.111"],"_bbp_last_reply_id":["0"],"_bbp_last_active_id":["461426"],"_bbp_last_active_time":["2026-07-16 17:59:51"],"_bbp_reply_count":["0"],"_bbp_reply_count_hidden":["0"],"_bbp_voice_count":["1"],"_bbp_engagement":["303921"],"_btv_view_count":["40"],"_bbp_topic_status":["unanswered"],"_bbp_notification_enabled":["303921"]},"test":"lalvarezuvigo-es"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/461426","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics"}],"about":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/types\/topic"}],"version-history":[{"count":0,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/461426\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=461426"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}