question about surrounding space in CST MWS

The model will be surrounded by a frame if the numerique values of its directions are specified. Will the corresponding setting affect a lot the results of simulation? In fact, I thought that surrounding space represented the zone of calculation. However, each time I complete Surrounding space with zero, the simulation normally works. I don’t really see the influence of surrounding space to the results .I am looking forward to your answer of this problem thank you

HI,
I can't completely get ur words..do u mean the background materials? or the distance between the model and bounding box?

yeah,I mean the Surrounding space frame located in the dialog box of background properties.How should I enter the values of the parameters like Xlow,Ylow,Zlow.......Is Surrounding space considerated as the calculation area?

Default is zero, and works well for many cases, which means you do not need to change anything at all in many cases. However you can also change the value so that you see different size of the calculation box. The size of course impacts the calculation. For instance, if you have a much smaller size than default, then I think you will clearly see the difference. How to choose the appropriate size really depends. For instance, some people believe that the margin should be no less than quarter wavelength. To sum up, the more simulations you run, the more experience you will gain.

lower Xdistance 就是把你建的模型X軸的負(fù)方向增加background properties，其他的也是一樣的理解，upper Xdistance就是X正方向嘍。為什么有這個(gè)設(shè)置呢，這也是考慮模型的外部環(huán)境，比如說(shuō)CST平面器件那個(gè)例子，X Y Z的邊界條件都是PEC， 此時(shí)設(shè)置了upper Xdistance 卻設(shè)置5倍的介質(zhì)板的厚度，我的理解就是在上方加了五倍介質(zhì)板的真空。因?yàn)楹芏鄸|西它是放在PEC的金屬盒子里，但是頂面又不是直接和PEC接觸。是的，增加了Surrounding space ，你就可以看到一個(gè)盒子框了，那個(gè)就是要計(jì)算的區(qū)域。

最近版主們，好像不怎么回帖了？

對(duì)了 你怎么不看幫助啊 我靠 英文這么 好看的話不費(fèi)勁啊
Surrounding space frame:
Apply in all directions: If this checkbox is activated, the value in lower X distance is applied in all directions. The remaining input fields are grayed out. Therefore, you do not need to enter the same value six times if it is the same for all directions.
Lower X / Upper X / Lower Y / Upper Y / Lower Z / Upper Z distance: This dialog group can be used to add some extra space around your structure. An open boundary, in particular, requires this extra space to operate properly. All numbers must be positive.

I did read the documents concerning the Surrounding space which does not clarifies the different results due to the different surrounding space.
I tried to expand the surrounding space and run the simulation again. But I got the same results except that the simulation time was longer compared with the former programming
Oh làlà, c’est pas normal

Thanks for everyone' explication
Does anyone know the reason why "I got the same results except that the simulation time was longer compared with the former programming "?

surrounding space就是模型的“最邊緣處”和boundary box的距離，如果是0的話，除了"open add space"以外，其它邊界會(huì)“緊貼”模型（相當(dāng)于外接六面體）。
假設(shè)有一個(gè)模型，網(wǎng)格劃分已經(jīng)“合適”了，這時(shí)如果稍微增大surrounding space的數(shù)值，會(huì)稍微增大整個(gè)計(jì)算區(qū)域（網(wǎng)格數(shù)目增大），同時(shí)又不影響模型細(xì)節(jié)處的網(wǎng)格劃分，這樣仿真結(jié)果不會(huì)有明顯改變但仿真時(shí)間會(huì)延長(zhǎng)（要計(jì)算的網(wǎng)格多了）。
對(duì)以上的猜測(cè)，可以看一下solver logfile，excitation time應(yīng)該保持不變。