管道式旁路流
Heat sink performance is impacted directly by how air flows through or around the fins of the heat sink. Ducting helps focus air flow through the fins, maximizing how much of the fluid is in direct contact with the fin surface area. This directly impacts flow resistance, which is limited by the “strength” of the fan or blower generating the flow. If we let air flow around the heat sink, that is considered bypass flow. Let’s define the differences between ducted, bypass, and free flow.
管道流
当流体通过密封通道或管道时，迫使所有流体通过散热器的翅片，则该流动被视为管道。风管的顶部与翅片尖端接触。
旁路流量
旁路流是管道流的修改，其中密封通道的壁不正好靠在散热器的边缘。散热器和通道壁之间的这个额外空间允许流动绕过翅片，因此得名。
通常，我们将垂直旁路称为在翅片尖端和管道顶部之间增加的额外间隙。流体流动将能够在翅片上方的空间中更自由地移动。
如果我们在散热器的侧面增加间隙，则被认为是水平间隙。如果水平旁路的宽度大于翅片间隙，则流体在旁路中的流动比在翅片之间可以更自由地流动。
在大多数仿真软件中，需要有某种边界来限制程序所经历的计算量。否则，你会要求你的计算机计算比你需要的更多。
精灵中的管道
Genie has a few different options when it comes to defining flow for your thermal simulation. Genie defaults to having ducted flow for all three flow types in the Flow Definition portion of a project. One flow type, standard fixed flow, has the option of adding bypass flow around your heat sink.
模仿精灵中的自由流动
您可以通过增加垂直和水平旁路来模仿精灵中的自由流动。通过添加所有这些额外的空间，您可以减少管道壁产生的任何边界层的影响，并使作用在散热器上的流动不受阻碍。只要确保使用流速而不是流速即可。流速是体积的，通过增加流动面积，您可以大大降低实际速度。
There you have it, ducted versus bypass flow. Try it out in Genie in the Flow Definition page of your project! Test out what works best for your custom heat sink design. If you need some assistance in determining the constraints of your flow, Contact Us to talk with experienced Boyd Design Engineers.
