I need to complete a thermal simulation on the nose of an aircraft constructed of a carbon-fiber resin material. I have values for the in-plane and out-of-plane thermal conductivity. Considering the geometry of the cone, I can't enter the thermal conductivities oriented with a rectilinear coordinate system (as is necessary in the material editor for this type of material). The analysis is for cooling an electronics system through the aircraft skin.
With the ongoing prolifieration of composite materials, having this capability would be significantly beneficial. If Autodesk could incorporate this ability into their simulation tool, it would be a product differentiiating capability.
I would like the collapsible Materials/BCs/ICs/Motion/Groups folders and subsections to stay how you left them, or at least auto collapse. I've realised I spend a large amount of time collapsing 'Material' and then each group in turn to easily access the ones at the bottom - all subsections auto expand when you assign parts to a group.
I would like to be able to simulate a nozzle that sprays water into an air stream. Ideally I would be able to view evaporation of the water into the air stream (evaporative cooling) and condensation of moisture from warm air onto the cold droplets of the spray (dehumidification).
It would be nice to have the ability to specify a spatially varying heat flux boundary condition, or in other words a heat flux profile or distribution. This could be done by defining a function of heat flux as a function of position on a surface with appropriate limits. As of right now, the only way to accomplish this is to break the surface into descrete surfaces and apply average heat fluxes to each region. This can be especially painful when you have a steep slope in the distribution of heat flux vs. position function.
This would be useful for applications where the heat flux applied to a surface is non-uniform, such as concentrated solar power applications where you might have a hot spot in the center and a profile much like a gaussian distribution.
This problem is quite common in oil and gas industry. During the oil refinery process, waste material usually consists of water and oil mixed together. Water and oil cannot mix, then causes oil droplets to float above water. It would certainly be nice to be able to assign two different liquid materials that interacts with each other as the simulation runs. Perhaps simulation of oil suction away from the "clean" water can be performed once this feature is in place.
Picture below shows concept of oil water separator.
Here is the 'topic' I submitted some days ago.
Because I have to use an emispherical and thin solid dome, immersed in a fluid domain, and it is made by conductive plastic material (it is obviously orthotropic), I didn't found, reading documentation, any indication about how to build a 'Local Coordinate System'
So, I should like to know if X Y and Z axis (indicated in Material Database panel) are global or local.
If they are global, this is a serious limit to this very fine software; if not, I really will appreciate any help to resolve this issue.
the answer (by Royce Abel- Autodesk) was:
The X, Y, and Z material properties are based on the global coordinates and you cannot define local material properties.
This would be an excellent comment to add to the idea station.
So, now I ask to insert in CFD the ability to manage Local Coordinate System for Solid Material definition (but not only)
There's been numerous occasions where simulation of water evaporations is needed. One example would be to simulate the water loss (through evaporation) for a heated processing chamber. The processing chamber processes sludge and liquid waste materials by heating it and extracting the water content.
The current CFD module for condensation is limited and it cannot fully capture water vapors moving in control volumes.
For an illustration, refer to the link below (under process flow):
The evaporation process happens in the heated Process Chamber.
Heat pipes are quite ubiquitous these days in electronic packaging. The short cut to model the heat pipe as a highly conductive (~50-100,000 W/mK) rod must be done very carefully as it does not take into account the heat transfer capacity based on temperature and tube diameter. If the one does not take into account these variables then the simulation will give extremely optimistic results.
It would be great if Simulation CFD had a Compact Material Model for heat pipes that would perform the necessary transfer curve for the model.
When the heat exchaner material was created it was decided that the default inlet condition of the material would be a 0 pressure. This configuration is perfect when you have only 1 heat exchanger, but many users will have multiple units in they model (CRAC data centers). Recently, I have seen more and more sealed data centers where there is no fresh air supply. This creates a problem because they need to use the 'heat_ex_inlet_is_flow_bc' flag to get the correct flow balance in the model, but at the same time they should have 1 of the heat exchangers setup as a pressure inlet to make sure that we are not over constraining the flow simulation.
Also, hiding the flag setting for the heat exchanger makes it very difficult for users to know that they need to use it.
I propose that the inlet condition for the heat exchanger be part of the material definition or maybe part of the general assignment window when you define the inlet and outlet surfaces. This way users will have to pick either pressure our flow rate inlet constraint.
We predict the operating point of fans within the model but could we not plot them on a graph?
Request from Maxime Bomme of Aplisim
With the addition of the solar heating to simCFD 2013, it would be great to be able to include the absorptivity in the material properties (in addition to emissivity). A lot of materials deployed in the outside world have very different emissivity/absorptivity ratios on purpose. Although you can trick the solar flux in the flag manager, it would be easier/more useful if you could just assign a material property called 'solar absorptivity' and let the user assign a value. That way, if there are multiple materials with differing absorptivities in the same model, the setup and results would be easier/more accurate.
We have heard requests from customers looking to model more plastic materials in Simulation CFD. In particular, MoldFlow users want to use some of the same materials they use in MoldFlow simulations.
PP+talc or PP+talc+GF
Do others have suggestions on specific materials that would he helpful? Let us know if you would benefit from additional materials in the default CFD material library.
Jon den Hartog
In Simulation CFD 2013 heat exchangers may be controlled by a specified supply temperature, a temperature difference, or a heat removal rate. However, many CRACs, CRAHs, and air conditioners supply air at a given temperature up until the point at which their capacity is exceeded. Beyond that temperature, the supply temperature will drift upward. Modeling this behavior would require a combination of some of the control modes currently available.
We understand there is some interest in this capability for certain users but are looking to see how wide the need is. If you see value in expanding the control options for heat exchanger materials to account for this behavior, let us know.
Radial resistance regions can be used to model complex filters, screens, etc without the burden of a highly detailed CAD model. These resistance regions should represent these components as accurately as possible, including cases where flow is purely radial.
When running a joule heating analysis it is very common to have surface contacts between connectors. Currently, to model those contacts you need to model them as volumes which isn't as straight forward and requires a fair amount of mesh at each contact location.
There is no indication that surface materials wouldn't work for joule heating problems, but making a simple model proves that heat is not generated at these surface contacts.
Could we have a way to monitor the junction temperature of CTM's as we run transient studies? Currently the only method is via monitor points, hopefully could have a smoother method.
Request from Maxime Bomme of Aplisim
It would be great if Simulation CFD would recognize the materials that are associated with Inventor part files without having to create rules within Simulation CFD. It would greatly improve the efficiency of my work flow. This should be very doable since you are now part of the Autodesk family. On another note, what about importing MatWeb data?
The light grey color for unassigned materials can be hard to spot when applying materials in the model window during setup. The background is a grey gradient, and many database materials are similar in color which complicates this future.
Suggestion is to show unassigned materials as a standout color (e.g. hunter orange), or better yet with a pattern that is not duplicated by the solid-colored options for database materials.
When none is entered, the cell should be left blank instead of the default 0 (zero).
For example, the electrical resistivity automatically shows 0 (zero) when it is intentionally left blank/undefined.
This is very confusing since zero resistivity (to me) means a superconducting material.
FYI: my material is an insulator with unknown electrical resistivity. I am trying to run some Joule heating simulation and do not want current to flow through this material which is in contact with a copper conductor.