I understand we can create Fluid Subdomains, but considering the fluids need to be seperated with a solid region, I can't immediately imagine where this could be of value? I'm sure I'm missing out on some obvious application areas but I'm coming up empty.
Kevin,
Heat exchangers typically always transfer heat from fluid to another. It could be water to water, water to air, refrigerant to air, refrigerant to water, ad infinitum. There is a tutorial on heat transfer that illustrates using fluid sub-domain to model heat exchange in a heat exchanger.
Ok, of course, I see that now. Sounds like a good common example, has anyone got a few more?
I do electronic packaging. The default fluid in my models is air. However I typically have a component in my assembly that is hermetically sealed package. This hermetically sealed package may either be a vacuum or an inert gas. I define this package as a fluid subdomain so I can change the air pressure to a vacuum or change the gas to something other than air.
vacuum space with volume, if no flow is defined, would be considered a closed cavity without flow conditions. I thought it could be excluded in the general setting so you don't have to do all that.?
Kevin,
I also find a fluid sub-domain useful in simulating ambient conditions surrounding the Flow model of interest. This on one project allowed me to relate wall temperatures on a pressure vessel with actual field measurements. Measuring temperatures inside vessels is not always possible but external temperatures are measurable. Of course the environment will have an effect which can be input as a BC. In this case I was trying to determine if two phase flow was present inside the vessel. If Flow predicted a wall temperature much higher than actual measured wasll temperature, then one possible explanation was a phase change inside the vessel.
In the heat exchanger example that David mentions, you define the default fluid as air for the external fluid and select an internal face (Flow Sim automatically recognizes the open volume) to define the fluid sub-domain where you define this separate volume as water.
Another point not related to subdomains, but similar to it for a transient analysis is Initial Conditions. You can define a region by a solid volume in SW and then in Flow disable that volume (so Flow thinks of this as a fluid) but assign different initial conditions to the volume than the global environmental/ambient conditions.
Kevin,
Heat exchangers typically always transfer heat from fluid to another. It could be water to water, water to air, refrigerant to air, refrigerant to water, ad infinitum. There is a tutorial on heat transfer that illustrates using fluid sub-domain to model heat exchange in a heat exchanger.