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Author Topic: Stair boundary layer  (Read 1842 times)

karl

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Stair boundary layer
« on: April 06, 2016, 09:39:42 am »

First of all, thank you for an excellent manual, tutorial and a good technical documentation of Pathfinder. As a new user, I found these resources particularly valuable while getting to know the model. I do, however, have a number of questions to which I haven't been able to track down the answer in the documentation. Therefore, I'll try this way of communicating my question. I’ll start with a general question on boundary layers in stairwells.

As I've understood it, I basically have two options/locations where I can modify the boundary layer settings: 1) Simulation -> Simulation Parameters -> Behavior (both for the SFPE and the Steering mode), and 2) Edit Profiles/Profile Properties -> Advanced. The first location refer to the model’s door boundary layers, whereas the other location refer to a “general” boundary layer for walls and other physical objects.

Now, let’s assume that I want to model the movement from one floor to another (ascending) using a stair in the Steering modelling mode. I connect the two floors with a 2 m wide (clear width), straight stair, and I choose not to limit the flowrate of that door (neither in the bottom nor on the top). So to the question: Assuming I’ve specified a 0.15 m "general" boundary layer in 2) above, and not ticked 1) (i.e., limited the door flow rate), will the agents in my model try to keep a 0.15 boundary layer to each of the stairwell walls while ascending the stair? In other words, will my stair flow rate be affected by the boundary layer, as it would in a normal, flat corridor?

Thank you for your input!
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karl

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Re: Stair boundary layer
« Reply #1 on: April 29, 2016, 02:42:55 am »

I've received a reply through e-mail, which I'd like to share with those of you who are interested (case number 36044).

Yes, your understanding of the two boundary layers is correct.

The Wall Boundary Layer ("general") applies to both rooms and stairs. It will change the movement on stairs. However, this is part of a larger cost calculation during movement, so occupants do not rigidly satisfy this rule.

I have attached a simple model. The stairs are 3 m wide. I did three cases:

1. Wall Boundary Layer = 0, 250 occupants. In this case the occupants do not maintain any distance from the wall.
2. Wall Boundary Layer = 1 m, 1 occupant. Here the single occupant does not have to account for interaction with other occupants, so they satisfy the 1 m specified layer.
3. Wall Boundary Layer = 1 m, 250 occupants. Here there is interaction with other occupants and the boundary layer is only one cost of many. In this case, the occupants attempt to avoid the boundary, but interaction with other occupants can cause them to move into the boundary layer.

Hope this helps,
Daniel Swenson
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Charlie Thornton

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Re: Stair boundary layer
« Reply #2 on: June 01, 2016, 08:51:45 am »

I've attached the additional images associated with that answer.

PTH file: https://drive.google.com/open?id=0B2DV68EcKn-nak5wa2VTQUhzaWM
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