{"id":228822,"date":"2010-01-23T14:26:31","date_gmt":"2010-01-23T19:26:31","guid":{"rendered":"tag:www.mentor.com:\/\/81bcbbbd498bc2923d294ff8e6bda4e2"},"modified":"2010-01-23T14:26:31","modified_gmt":"2010-01-23T19:26:31","slug":"blog-postquantitavely-seeding-the-flow","status":"publish","type":"post","link":"https:\/\/mereja.media\/index\/228822","title":{"rendered":"blog post:Quantitavely Seeding the Flow"},"content":{"rendered":"<p>I think that we can all agree that one feature of CFD over test is the ability to visualize where the flow is going.\u00a0 It is quite easy in CFD analysis tools, at least in our tools, to seed the flow any where within the solution and follow particles upstream and\/or downstream.\u00a0 The limitation of this is that it is the results are qualitative.\u00a0 CFD has the capability, without an extreme amount of extra effort, to quantify where the flow goes.<\/p>\n<p>As an example I have constructed a partial model of a somewhat reasonable depiction of a 1U server in FloEFD.\u00a0 Each fan is fixed at 15 cfm where 2% (arbitrarily chosen) of the fluid that it delivers it tagged with a fluid marker.\u00a0 For instance,\u00a0 the fluid that Fan 3 supplies is 98% air and 2% \u201cAir-Fan 3?.\u00a0 \u201cAir-Fan 3? has the same fluid properties as air, not arbitrarily chosen.\u00a0<!--content--> There is also geometry that represents the power supply, which also delivers 15 cfm.\u00a0 The heat sinks are a porous media of reasonable flow impedance.\u00a0 The optional \u201cperf\u201d will be considered in another post to see if I can use it to create a more robust design in the event of a fan failure.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-838 aligncenter\" src=\"http:\/\/s3-blogs.mentor.com\/johnwilson\/files\/2010\/01\/fan_location-520x274.jpg\" alt=\"fan_location\" width=\"520\" height=\"274\" \/><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-medium wp-image-836\" src=\"http:\/\/s3-blogs.mentor.com\/johnwilson\/files\/2010\/01\/layout-520x334.jpg\" alt=\"layout\" width=\"520\" height=\"334\" \/>The image below shows a qualitative depiction of the area of influence from Fan 1.\u00a0 Nice, but we can get more information from the marking of the flow.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-844 aligncenter\" src=\"http:\/\/s3-blogs.mentor.com\/johnwilson\/files\/2010\/01\/flow_trajectories-520x494.jpg\" alt=\"flow_trajectories\" width=\"312\" height=\"296\" \/><\/p>\n<p>Below is a cross section through the center of the fans that quantifies the area of influence from Fan 1 and Fan 3.\u00a0 I have clipped out the area of less than 10% influence.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-medium wp-image-872\" src=\"http:\/\/s3-blogs.mentor.com\/johnwilson\/files\/2010\/01\/air-fan-1-520x283.jpg\" alt=\"air-fan-1\" width=\"520\" height=\"283\" \/><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-medium wp-image-874\" src=\"http:\/\/s3-blogs.mentor.com\/johnwilson\/files\/2010\/01\/air-fan-3-520x283.jpg\" alt=\"air-fan-3\" width=\"520\" height=\"283\" \/>To drive home the quantification I have tabulated how much air each heat sink is receiving from each fan.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-880 alignleft\" src=\"http:\/\/s3-blogs.mentor.com\/johnwilson\/files\/2010\/01\/table_no_perf.jpg\" alt=\"table_no_perf\" width=\"215\" height=\"371\" \/><\/p>\n<p>You can see that most of the flow that the heat sinks receive comes from Fan 2 and Fan 3.\u00a0 Ideally my heat sinks wouldn\u2019t be so reliant on flow from a particular fan.\u00a0 My plan is to see if I can help the situation by adding a perforated plate between the fans and the downstream heat sinks.\u00a0 Or maybe I will look at what happens when Fan 3 fails.\u00a0 I do think that having this type of output would be useful in maximizing the airflow management of the design.<\/p>\n<p>There is a similar, but more evolved, approach available in FloVENT via the \u201ccapture index\u201d which is very useful in Data Center design.\u00a0 Google it and check it out.\u00a0 Also, I\u2019d love to here any thoughts about the usefulness of this approach.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/feeds.feedburner.com\/~r\/mgc_mechanical\/~4\/dtEkEY536do\" height=\"1\" width=\"1\"\/><\/p>\n","protected":false},"excerpt":{"rendered":"<p>I think that we can all agree that one feature of CFD over test is the ability to visualize where the flow is going.\u00a0 It is quite easy in CFD analysis tools, at least in our tools, to seed the flow any where within the solution and follow particles upstream and\/or downstream.\u00a0 The limitation of [&hellip;]<\/p>\n","protected":false},"author":4581,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[],"class_list":["post-228822","post","type-post","status-publish","format-standard","hentry","category-news"],"_links":{"self":[{"href":"https:\/\/mereja.media\/index\/wp-json\/wp\/v2\/posts\/228822","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mereja.media\/index\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mereja.media\/index\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mereja.media\/index\/wp-json\/wp\/v2\/users\/4581"}],"replies":[{"embeddable":true,"href":"https:\/\/mereja.media\/index\/wp-json\/wp\/v2\/comments?post=228822"}],"version-history":[{"count":0,"href":"https:\/\/mereja.media\/index\/wp-json\/wp\/v2\/posts\/228822\/revisions"}],"wp:attachment":[{"href":"https:\/\/mereja.media\/index\/wp-json\/wp\/v2\/media?parent=228822"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mereja.media\/index\/wp-json\/wp\/v2\/categories?post=228822"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mereja.media\/index\/wp-json\/wp\/v2\/tags?post=228822"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}