Hi,
I have a problem simulating underground car park which is required to be run for 20 minutes after the fire souce catch fire. Some research was done and i also viewed a past example. Here. But the desired result still can not be achived.
Some unsolved question:
1. Massive sudden increase in velocity magnitude.
2. Divergent occour at around the 600th Time Step.
3. How does divergent happen? What causes it to happen?
4. Whether the parameter inputed below are appropriate.
Hope the below detail helps.
General details:
Height 3m, The car park was cut into 2 zone as it was too huge.
For 9 air changes needed, one free vent inlet.
Materials:
Ducts, Volume = Air (variable)
"Fire Source" = Resistance (Fire):
Through Flow K = 0.5
Normal Direction 1 K = 0
Normal Direction 2 K = 0
Conductivity = 1 W/m-k
(all constant)
Flow direction of Fire material picked towards up (Z vector)
Jet Fan "Fan" = Custom Internal Fan ("Fan"), by sizes and preferences as manufactured:
Flow = 630 m3/h
Rotational Speed = 0 RPM
Slip Factor = 0.7
(all constant)
Flow direction towards the front of the jetfan (x and y vectors depend on location in the parking lot)
Boundary Conditions:
"Fire Source" =
(Volume) Total heat generation 4 MW
Steady state
Temp dependent - Disabled
(Surface) Scalar 1, Steady state.
Ducts:
(Fresh Air Flow) (Surface) Volume Flow rate 6.825m/s each. Temperature 20DegC. Scalar 0.
(Exhaust Air Flow) (Surface) Volume Flow rate 3.4125m/s each.
Steady state.
Free Inlet:
Pressure = 0
Initial Conditions:
Air Volume = Scalar 0
Mesh Size
Auto with adjustments in the fans, fire source and ducts.
Solver:
Control: Solution Mode = Transient
Time Step Size = 0.03
Stop Time = 1200
Inner Iterations = 1
Time Step to Run = 40000
Solution Controls:
Intelligent solution control = Enable
Advection = 5
Result Quantities:
Scalar = on
Smoke Visibility = On; Parameters:
Extinction Coefficient = 37000 ft2/lb
Sign Visibility Constant = 3
Combustion Particulate Yield: 0.008
Physics:
Flow = on
Incompressible.
Heat Transfer = on
Auto forced convection = off
Gravity Direction = 0,0,-1
Radiation = off
Advanced:
General Scalar:
Diffusion coefficient: 0.12 cm2/s.
Sorry for the long post. This is for our project.
Thank you.
LJX,
Hi,
Here are my initial impressions:
I hope that helps.
Thanks,
Jon