Table of Contents
PyroSim is designed to help you interactively create complex geometry. The 2D View provides a collection of geometry creation tools. These tools allow you to quickly draw rectangular obstructions, angled walls, blocks, vents, and rooms. Several of these tools have an analog that creates holes instead of solid obstructions. All geometry creation tools are located on the toolbar at the left side of the 2D View.
Some of these tools allow you to create and edit objects that are not constrained to the FDS mesh. In these cases, PyroSim will automatically convert the shapes to mesh-based blocks when the FDS input file is created. You can also preview these bocks by clicking View, then selecting Preview as Blocks.
All of the geometry tools in this chapter are fully supported by the undo/redo system. If you change your mind about the placement of an object you have just created, just click Edit, then click Undo.
Most objects can be edited with the Selection
tool. This tool is located in the toolbar above the 2D and 3D views. Once you
have activated the Selection tool, click on the object you would like to modify.
Blue nodes or handles will appear on the object where it can be modified. By dragging
these handles you can quickly make changes to the existing object.
You can edit the settings for any tool by clicking the
Tool Properties
button located at the bottom of the toolbar. Options such as initial surface type,
color, sawtooth, and depth can all be edited in the Tool Properties dialog.
You can create simple rectangular obstructions with the Draw an Obstruction
tool. Objects created with this tool will be directly
translated into FDS obstruction records. To create objects with this tool, follow these steps:
Click the Draw an Obstruction
button.
Click the Tool Properties
button to set the obstruction properties. Define the Min Z and Max Z coordinates and Surface Property for the obstruction.
Position the mouse pointer where you want to begin creating the obstruction, then press and hold the left mouse button. The mouse coordinates are displayed in the lower-left corner of the view to help you accurately place the object.
Drag the mouse to the opposite corner of your desired obstruction.
Release the mouse button.
You can create simple rectangular holes with the Draw a Hole
tool. The hole version of this tool is identical to the
obstruction version, except it will create FDS hole records.
You can create walls in PyroSim using the Draw a Wall
tool. This tool is only available in the Top View
. Walls can be rotated freely in the top
view and are not constrained by the FDS mesh.
To create a wall using the wall tool:
Click the Draw a Wall
button.
Click the Tool Properties
button to set the wall properties.
Position the mouse pointer where you want to begin creating the wall, then press and hold the left mouse button. The mouse coordinates are displayed in the lower-left corner of the view to help you accurately place the object.
Drag the mouse to the end point of the wall.
Release the mouse button.
Walls have an associated thickness property. When you create a wall you are positioning either the two internal or two external corners -- not the centerline. To toggle the direction that the width of the wall extends, press the SHIFT key while creating the wall. If you release the SHIFT key before you have completed the wall, the thickness direction will return to its default setting.
PyroSim will automatically convert walls into mesh-based FDS objects when required. If you have created a diagonal wall and want to preview the obstructions that will be created for FDS, make sure there is a mesh around the wall, and click View, then select Preview as Blocks.
You can create holes in the same manner as walls using the Draw a Wall Hole
tool. The hole version of this tool is identical to the
solid version, except it will create holes rather than solid geometry.
You can fill individual blocks using the Draw a Block
tool. To create blocks using this tool,
simply click a cell you would like to fill. You can also click and
drag the mouse across the mesh to "paint" blocks.
The depth of the cells will not necessarily be the depth of a cell in the current
mesh, however. The depth and other options for this tool can be edited in the
Tool Properties
dialog.
This tool operates on the currently selected grid. To select a grid, click View, click Select Grid, then select the grid you would like to work with.
This tool is generally more useful when the Snap to Grid option is selected. To enable grid snapping, click View, then select Snap to Grid. When grid snapping is disabled, this tool will create many small, overlapping obstructions.
You can create block holes using the Draw a Block Hole
tool. The hole version of this tool is
identical to the solid version, except it will create holes rather than
solid geometry.
The Draw a Room
tool gives you a fast way to define the four walls of a room.
This tool is only available in the Top View
.
To create a room using the Draw a Room tool:
Click the Draw a Room
button.
Click the Tool Properties
button to set the properties.
Position the mouse pointer at one corner of the desired room, then press and hold the left mouse button.
Drag the mouse to the opposite corner of the desired room.
Release the mouse button.
By default, the Draw a Room tool expects you to define two inner corners of the room and the thickness of the walls will extend outward. You can press the SHIFT key while creating the room to make the thickness of the walls extend inward. If you release the SHIFT key before you have completed the room, the thickness direction will return to its default setting.
You can create vents using the Draw a Vent
tool. Vents have general usage in FDS to describe 2D planar objects. Taken literally, a vent can be used to model components of the ventilation system in a building, like a diffuser or a return. In these cases, the vent coordinates form a plane on a solid surface forming the boundary of the duct. No holes need to be created through the solid; it is assumed that air is pushed out of or sucked into duct work within the wall.
You can also use vents as a means of applying a particular boundary condition to a rectangular patch on a solid surface. A fire, for example, is usually created by first generating a solid obstruction and then specifying a vent somewhere on one of the faces of the solid with the characteristics of the thermal and combustion properties of the fuel.
There are two reserved surface types that may be applied to a vent: OPEN and MIRROR. For more information on these types, see the chapter on Surface Properties.
There is one exception to the rule that vents must be prescribed flush against a solid obstruction or external boundary. A vent that is prescribed in the interior of the domain, without any adjacent solid surface, can act as a fan.
To create a vent in the 2D View, you can follow these steps:
Click the Draw a Vent
button.
Click the Tool Properties
button to set the vent properties.
Position the mouse pointer at one corner of the desired vent, then press and hold the left mouse button.
Drag the mouse to the opposite corner of the desired vent.
Release the mouse button.
The new vent will lie in the plane parallel to the viewing plane. For example, if you are using the Top View when you draw the vent, the vent will lie in the Z plane.