|
Home / Examples / Fluid Analysis [Bernoulli] / Example 13: Room Ventilation (Air Age Calculation)
Example 13: Room Ventilation (Air Age Calculation)
General
-
Ventilation in the room is analyzed.
-
Air age, air residual lifetime, and air lifetime are analyzed using diffusion analysis.
See Diffusion Analysis of technical note for more information about air age, air residual lifetime, and air lifetime.
-
Steady-state analysis of the fluid solver is applied and air age is solved by diffusion analysis.
-
Unless specified in the list below, the default conditions are applied.
-
Obtain this session's project file. (Right-click and choose 'Save link as')
-
Results will vary depending on Femtet version and the PC environment.
Analysis Space
|
Item |
Settings |
|
Analysis Space |
3D |
|
Model Unit |
m |
Analysis Conditions
|
Item |
Tab |
Setting |
|
Solver |
Solver Selection |
Fluid Analysis [Bernoulli] |
|
Analysis Type |
Fluid Analysis |
Steady-state Analysis |
|
Setup Details |
Fluid Analysis |
Select [Calculate quasi-steady state in the case of non-convergence]. |
|
Diffusion Analysis |
Fluid Analysis |
Select Diffusion Analysis |
|
Diffusion Analysis Setting |
Fluid Analysis |
Analysis Type: Air Age Analysis |
|
Meshing Setup |
Mesh |
General Mesh Size: 0.3 [m] |
Model
The air domain is shown as below. The model represents a room with a ventilator and a door. The door is assumed to be opened.
Body Attributes and Materials
|
Body Number/Type |
Body Attribute Name |
Material Name |
|
3/Solid |
Room |
000_Air * |
* Available from the material DB
Boundary Condition
|
Boundary Condition Name/Topology |
Tab |
Boundary Condition Type |
Setting |
|
Door/Face |
Fluid |
Inlet/Outlet |
Natural Inflow/Outflow |
|
Fan/Face |
Fluid |
Outlet |
45 [m3/min] |
Results
Streamlines of the quasi-steady state are shown below.
Isosurface contours of the air age are shown below. Specified values are 10[s], 20[s], and 30[s].
The isosurface indicates how far the air flows into the room from the door.
You can see the boundary moves from the door toward the ventilator over time.
|
|
Isosurface Contour |
|
Air Age Specified Value for Isosurface: 10 [s] |
|
|
Air Age Specified Value for Isosurface: 20 [s] |
|
|
Air Age Specified Value for Isosurface: 30 [s] |
|
Isosurface contours of the air age are shown below.
The place near the wall has larger values, indicating its ventilation will take longer time.
Isosurface contours of lifetime of the air [normalized] are shown below.
Efficient ventilation is achieved where the value is 1 or less.
The efficiency of ventilation is deteriorated where the value is greater than 1.
Near the wall, the value is 4 or more. Required ventilation is four times the usual.
