有限元分析：究竟什么是好網(wǎng)格？

Good mesh need resolve physics, not follow the CADmodel.

好網(wǎng)格應(yīng)該很好地描述物理本質(zhì),而不是符合CAD模型。

A good mesh is always associated with the physics. Whenyou change your boundary conditions, or change your loadconditions, or change analysis types, or change flow models, goodmesh (with the identical geometry) may turns to be badmesh.

好網(wǎng)格必須始終反應(yīng)物理本質(zhì)。當你改變邊界條件、載荷、分析類型或者流體模型時,質(zhì)量好的網(wǎng)格可能會變成差網(wǎng)格。

The accuracy advantage of hex meshis no longer existing anymore, for most engineering problems.

對于很多工程問題,六面體在精確度上的優(yōu)勢已經(jīng)不存在了。

When the software vendor needjustify that his meshing software is in the high-end (of courseprice is usually in the high end as well), he will tell you thesoftware allows you to all sorts of manual controls. The hiddeninformation is only manual controls can generate better mesh.

當軟件供應(yīng)商向你推銷網(wǎng)格劃分功能時,他會告訴你這款軟件支持各種各樣的手動劃分網(wǎng)格的方法。隱含意思就是手動控制網(wǎng)格才能得到好網(wǎng)格。

Yes, to salesman, good mesh need manualcontrol. But to engineer, you need understand this is misleading. Agood meshing software should have the intelligence to analyze theunderlying geometry: calculating curvatures, finding gaps; findingsmall features; finding hard edges; finding sharpangles, applying sensible default settings….

是的,對于銷售者來說,好網(wǎng)格需要手工控制。但對于工程師而言,你應(yīng)該知道這其實是在誤導。一個好的網(wǎng)格劃分軟件應(yīng)該智能地去分析它將要劃分的幾何模型:計算曲率、識別間隙、識別小特征、識別銳邊、識別尖角,然后進行合理的默認處理(無需人工干預(yù))。

<譯者按:這也許是前處理軟件的發(fā)展趨勢>

Fine mesh does not mean good mesh.The purpose of meshing is toget solutions in discrete locations. Good mesh is the mesh thatserves your project objectives. So, as long as your results are: 1)physical; and 2) accurate enough for yourproject, your mesh is sufficiently good.

精致的網(wǎng)格不等于好網(wǎng)格。畫網(wǎng)格的目的是得到離散點上的值。只要能滿足工程需要就是好網(wǎng)格。保證兩點:1)表達物理本質(zhì);2)達到工程所需的精度。

Another example of thismisunderstanding is that most users always use full 3D model. Intheir eyes, 3D full model is “realistic”. However, if the problemis symmetry, using portion of your geometry (therefore lessnodes/elements) will produce better results because the symmetriccondition is exactly enforced. If the problem is axis symmetric, 2Dresults is far more accurate than most 3D results.

這一誤區(qū)的另一個表現(xiàn)是:總是使用完整的3D模型。在他們眼里,完整的3D模型才是最逼真的。然而,如果問題是對稱的,使用模型的一部分(這樣可以減少節(jié)點和單元數(shù)量)可以獲得更好的結(jié)果(因為這樣會精確反應(yīng)對稱性)。如果問題是軸對稱的,使用2D模型比3D模型更精確。

Currently, CAE still replieson meshing. Good mesh should:

1. be able to resolve the physics to bestudied;

2. have reasonable quality so that the solver will notfail;

3. simplify the geometry based onphysics;

4. be problem specific;

5. meet your project requirements

目前,CAE仍然依賴于網(wǎng)格劃分。好網(wǎng)格應(yīng)該做到以下幾點:

1、能夠解決所研究的物理問題;

2、網(wǎng)格質(zhì)量合理,避免計算失敗;

3、基于物理本質(zhì)簡化幾何模型;

4、具體問題具體對待(對同一個幾何模型做不同的分析,可能需要劃分不同的網(wǎng)格)

5、滿足工程需求

內(nèi)容轉(zhuǎn)自:

http://caewatch.com/top-5-misunderstandings-on-good-mesh/