IES-VE User Forum

I have managed to draw a small wind catcher with doors set up as the louvres. I have set up an opening type in macroflo. I have run apache sim and from the vista pro viewer the wind catcher seems to be working as intended.

I want to model this in Microflo but because I am modelling louvres the "import opening flows" and "window opening position" is not really applicable. It is a louvre not a window.

I am also intending to carry out a similar exercise with other large free air louvres as part of a natural ventilation scheme. I am going to have to same issue with these openings because they are not windows.

Any ideas on how this can be resolved?

Q> I want to model this in Microflo but because I am modelling louvres the "import opening flows" and "window opening position" is not really applicable. It is a louvre not a window.

Boundary conditions where air enters a Microflo model are set up as constant mass flux boundaries, usually called "Inlets" in other CFD codes.

In Microflo these constant mass flux boundary conditions are call a "Supply" or a "Diffuser". These are just the naming convention used. Under the hood they are boundary conditions they are "Inlet" boundaries - where you know the mass flux, and because the flow is assumed to be incompressible, the velocity and volumetric flow rate.

So all flow boundaries where air enters the model are set up with a volumetric flow rate and area and flow direction, whether they are windows, doors, louvres, diffusers etc etc.

When you run an apacheSim/Macroflo model Macroflo calculates the flow through each opening in the model based on the opening size, type (free area etc), and exposure type that you set in Macroflo. It is these flow rates that get set up using "Inlet" boundary conditions in Microflo.

Microflo doesn't care if the "Inlet" boundary is representing a window, door, diffuser or anything else. It just cares about the flow rate, the area over which that flow rate is applied, and the direction of flow - assumed to be along the normal for imported Macroflo boundaries, but they can be changed, or set up manually for a 4-way diffuser for example.

So when the import window in Microflo talks about "opening flow" it is talking about any Macroflo predicted opening flow, including doors and louvres.

The "Window opening position" is used when you specify an opening that has an "Openable area" that is less than 100% in Macroflo. E.g., if you say a window is open 50% then the thermal model doesn't need any further info but Microflo needs to know where that 50% is. So the boundary import function allows the user to say it is a the top, bottom, left or right. It is rather crude but there is no reason why you couldn't import the boundaries, note the flow rate and temperature, delete the boundary and then redraw the boundary exactly where you want it.

If the "Openable area" is 100% in Macroflo then "Window opening position" has no effect in Microflo as the whole of the ModelIT surface is used as the flow boundary.

In short: don't worry that it says window, use it to import louvre flows.

I am a beginner in the Environmental Building Design. So I would be grateful if you guide me about my question.
I am using Microflo to simulate the building for natural ventilation. After running the simulation for different positions of openings I see in the Microflo viewer in colors. However, I do not know how to interpret the colors in order to find which locations for openings are better? How it should be? in what color?

Hi MaPenn,

Have you seen the film Spinal Tap? There is a scene when the guitarist is explaining why his amp is so good, saying that the volume goes upto 11 while all the other amps only go up to 10. The interviewer asks why not make 10 the highest volume and the guitarist says no my amp is better it goes up to 11.

What I am saying is that the colours in Microflo are arbitrary. Although the blue is always at the bottom of the scale and the red is at the top of the scale. You can go to "display settings" and change the scale to make the value at the top and/or bottom of the scale to anything you want. Therefore there is no way to answer how you should interpret the colours.

It is the variable values that you should be interpreting. The air temperature, air velocity, PMV, PPD, and age of air for example.