搜索
本例演示如何建立 COMSOL Multiphysics® 5.2 版中引入的有效 H-B/B-H 曲线材料模型，用于在频域分析中对磁性材料建模。模型还将有效 H-B/B-H 曲线模型的结果与基于线性和非线性 H-B/B-H 曲线材料模型的结果进行了比较。
案例下载 -
cn.comsol.com/model/33981
本例最初由 Albert Witarsa 在美国西雅图华盛顿大学的 Bruce Finlayson 教授的监督下制定，它是研究生课程的一部分，其中的任务包括通过数学建模来评估微流体领域的潜在专利权。
模型探讨 H 型微槽的扩散分离。H 型槽使两种不同的层流在可控时间段内接触，接触面界限非常明确，通过控制流率，可以控制通过扩散从一个流传递到另一个流的物质量。
模型利用“层流”和“稀物质传递”接口充分捕捉槽内的分离。
案例下载 -
cn.comsol.com/model/19
本例介绍如何在二维和三维模式下对微波的矩形波导建模。一个中空波导可以传导两种电磁波：横磁波 (TM) 或横电波 (TE)。
模型分析在传播方向上没有电场分量的 TE 波，更具体地说，对于这些模型，您可以选择特定的频率和波导尺寸，使 TE10 成为单一传播模式，在该模式下，电场只有一个非零分量，即具有两个节点的正弦曲线，每个波导壁上各有一个节点。
案例下载 -
cn.comsol.com/model/1421
“B-H 曲线检查器”App 可用于检查和优化通过实验测得的 B-H 曲线。该 App 可以在难以测量的过通量区域生成曲线数据，还可以消除 B-H 曲线斜率的非物理波动，这些波动可能导致数值不稳定。
该 App 从两个方面评估原始的 B-H 曲线。首先是从物理角度检查曲线的外推是否合理。然后检查曲线的斜率是否平滑。优化算法主要分别基于同步指数外推法和线性插值法。
该 App 需要将文本文件中定义的原始曲线数据作为输入。导入曲线后，App 将检查它是否需要优化。通过单击“优化”按钮，用户可以生成优化的曲线数据，并将这些数据导出到文本文件。
案例下载 -
cn.comsol.com/model/71651
In a heat transfer convective boundary condition that could for example be h*(To-T), where h is your heat transfer coefficient.
知识库 -
cn.comsol.com/support ...
For more information, see ./lmstat -<b>h</b>
mac OS X
Start the Terminal application and run these commands:
cd /Applications/COMSOL61/Multiphysics/license/maci64
`.
知识库 -
cn.comsol.com/support ...
The relationship between wavespeed, c, maximum mesh size, h, and time step length, Δt, is known as the CFL number:
CFL = cΔt/h
We have already manually defined the maximum mesh size to be 1/N of the local wavelength (as described above), so this can re-written in terms of the frequency f, and N the number of elements per local wavelength:
CFL = fNΔt
or, rearranging:
Δt = CFL/Nf
With the default second order, quadratic, mesh elements, the CFL number should be less that 0.2, and a value of 0.1 proves to be near optimal, it is helpful to define this CFL number as a Global Parameter as well.
知识库 -
cn.comsol.com/support ...
COMSOL Multiphysics usually uses an interpolation function with a local table to define the B-H curve. You can also plug in your own B-H curves by adding the B-H Curve material property to a new magnetic material.
How the Extrapolation of the B-H Curve Affects the Simulation
In the Settings window of the B-H Curve interpolation function, you can click the Plot button to visualize the B-H curve.
COMSOL 博客 -
cn.comsol.com/blogs/how ...
B-H 曲线通常用于描述施加的磁场引起铁磁材料产生的非线性磁化行为。在这篇博文中，我们将使用 COMSOL Multiphysics® 软件 5.5 版本中的一个的演示 App 来展示 B-H 曲线如何影响磁分析，以及如何改进。
COMSOL Multiphysics 通常使用带有局部表的插值函数来定义 B-H 曲线。还可以通过将 B-H 曲线 材料属性添加到新的磁性材料来插入自己的 B-H 曲线。
COMSOL 博客 -
cn.comsol.com/blogs/how ...
矢量的瞬时模变量 现在可以将新变量添加到 phys.normXi = sqrt(real(Xx)^2+real(Xy)^2+real(Xz)^2) 表单中，其中，phys 是任意物理标记的占位符，如 ewfd；X 是物理量的占位符，如电场 (E)、磁场 (H) 等。为时谐矢量波生成可视化效果时，这些变量尤其有用。 与传统的模定义（右图）相比，弯曲金属表面上表面电流密度的瞬时模（左图）更加直观地显示了波特性的动态效果。
产品 -
cn.comsol.com/release/6.2 ...
矢量的瞬时模变量 现在可以将新变量添加到 phys.normXi = sqrt(real(Xx)^2+real(Xy)^2+real(Xz)^2) 表单中，其中，phys 是任意物理标记的占位符，如 ewfd；X 是物理量的占位符，如电场 (E)、磁场 (H) 等。为时谐矢量波生成可视化效果时，这些变量尤其有用。 与传统的模定义（右）相比，弯曲金属表面上表面电流密度的瞬时模（左）更加直观地显示了波特性的动态效果。
产品 -
cn.comsol.com/release/6.2 ...
Thus, the field problem is described by a coupled A-H field formulation [1]. The magnetic field strength is used in the superconducting domain, whereas the remaining domains are treated with the magnetic vector potential.
[1] Bortot, Lorenzo, et al. "A Coupled A–H Formulation for Magneto-Thermal Transients in High-Temperature Superconducting Magnets."
论文和技术资料 -
cn.comsol.com/paper/94851
A COMSOL Multiphysics® model of our apparatus has been created in order to simulate the pressurizations of our nanoparticles by Deuterium. Using reference measurements during a cooling process, we calibrated the model so that its thermal aspects reflect the ones of our experimental set up.
To reproduce the pressurizations, the following variables are parameters : the location of the heat source and the conductivity of the nanoparticles.
论文和技术资料 -
cn.comsol.com/paper/15715
A Polysilicon H-beam is a micro-machined structure consisting of two primary members connected by a third member of much lower width and much greater aspect ratio.
论文和技术资料 -
cn.comsol.com/paper/19399
Materials based H2 storage systems for light duty vehicles need to meet challenging performance targets that have been developed by the FreedomCAR and Fuel Partnership. An alternative approach is to mix metal hydride materials with materials that enhance thermal conductivity and compact the composite material in order to obtain a H2 storage system with a low volume.
论文和技术资料 -
cn.comsol.com/paper/12000
Hydrogen Embrittlement (HE) is one of the mechanisms responsible for premature failure of structures. In the context of environmental sustainability, it is compelling to improve or conceive new processes and/or new materials capable of reducing fracture induced by HE. We analyzed the influence of the oxide layer on the permeability of hydrogen.
论文和技术资料 -
cn.comsol.com/paper/6588
You can now convert the associated B-H or H-B curve, which was previously supported only for stationary and time-dependent studies, into an effective B-H or H-B curve using the newly added Effective Nonlinear Magnetic Curves Calculator app. For a B-H curve, the first column represents H values and the second column represents B values and vice versa for an H-B curve.
COMSOL 博客 -
cn.comsol.com/blogs/model ...
Multigrid methods (MG) belong to the fastest solvers for partial differential equations. The key for this is an appropriate composition of the algorithmic components [1,2,4]. The multigrid solver implemented in COMSOL Multiphysics® is analyzed with respect to components and with respect to its numerical properties.
论文和技术资料 -
cn.comsol.com/paper/15414
该 App 与有效非线性本构关系 功能相辅相成，“AC/DC 模块”中基于磁的接口支持有效 HB/BH 曲线材料模型，这种材料模型可用于在频域仿真中近似模拟非线性磁性材料的特性，避免全瞬态仿真所需的额外计算成本。
有效 HB/BH 曲线材料模型需要定义为插值函数的有效 Heff(B) 或 Beff(H) 关系。这个实用的 App 可用于计算从材料的 H(B) 或 B(H) 关系开始的插值数据。
H(B) 或 B(H) 关系的插值数据可以从文本文件导入，也可以输入在表格中。随后，App 将采用两种不同的能量法计算 Heff(B) 或 Beff(H) 关系的插值数据，得到的有效材料属性可以导出为 COMSOL 材料库文件，进一步用于 COMSOL Multiphysics® 软件磁场 接口中的模型。
案例下载 -
cn.comsol.com/model/30941
从 COMSOL Multiphysics 5.2 版本开始，可以使用 AC/DC 模块中的非线性磁性材料数据库中的非线性磁饱和曲线进行频域仿真。您可以使用新添加的有效非线性磁曲线计算器仿真 App 将关联的 B-H 或 H-B 曲线（以前仅支持稳态和瞬态研究）转换为有效的 B-H 或 H-B 曲线。
COMSOL 博客 -
cn.comsol.com/blogs/model ...