Hi all,
I am running the convection-box cookbook and I wish to have the run stop when it has reached steady state. I am actually interested in getting a reliable number of digits for the steady state vrms, heat flux, avrg T, etc … and since I wish to push it to Ra=1e6 and may be higher with higher and higher resolutions I do not want to set an arbitrary end time.
I am therefore trying to use the steady state Termination criterion as follows (which I copy-pasted and adapted from the box_steady_state_terminate.prm test):
subsection Termination criteria
set Termination criteria = steady state heat flux, steady state temperature, steady state velocity
subsection Steady state heat flux
set Maximum relative deviation = 1e-5
set Time in steady state = 0.1
set Boundary indicators = top,bottom
end
subsection Steady state temperature
set Maximum relative deviation = 1e-5
set Time in steady state = 0.1
end
subsection Steady state velocity
set Maximum relative deviation = 1e-5
set Time in steady state = 0.1
end
end
My problem is as follows: the run stops at time 0.1 no matter the relative deviation values that I input (1e-5 or 1e-11). By the way my end time is set at 0.5. This means that either I don’t understand what “Time in steady state” mean or there is a bug.
Looking at the manual, the definition for “Time in steady state” is “The minimum length of simulation time that the system should be in steady state before termination” which I interpret as the required time interval during which steady state has been reached according to the relative deviation. However, if my run stops at t=0.1, this would mean that it has been at steady state all along, which is nonsense.
Any idea/comment on what I am doing wrong?
Here is the entire prm file:
set Dimension = 2
set Use years in output instead of seconds = false
set End time = 0.5
set Output directory = output
set Pressure normalization = surface
set Surface pressure = 0
Stop the model run when a steady state heat flux is reached.
Some of the models do not reach steady state and will continue
until the end time is reached.
subsection Termination criteria
set Termination criteria = steady state heat flux, steady state temperature, steady state velocity
subsection Steady state heat flux
set Maximum relative deviation = 1e-5
set Time in steady state = 0.1
set Boundary indicators = top,bottom
end
subsection Steady state temperature
set Maximum relative deviation = 1e-5
set Time in steady state = 0.1
end
subsection Steady state velocity
set Maximum relative deviation = 1e-5
set Time in steady state = 0.1
end
end
subsection Geometry model
set Model name = box
subsection Box
set X extent = 1
set Y extent = 1
end
end
subsection Initial temperature model
set Model name = function
subsection Function
set Variable names = x,z
set Function constants = p=0.01, L=1, pi=3.1415926536, k=1
set Function expression = (1.0-z) - pcos(kpi*x/L)sin(piz)
end
end
subsection Boundary temperature model
set Fixed temperature boundary indicators = bottom, top
set List of model names = box
subsection Box
set Bottom temperature = 1
set Top temperature = 0
end
end
subsection Boundary velocity model
set Tangential velocity boundary indicators = left, right, bottom, top
end
subsection Gravity model
set Model name = vertical
subsection Vertical
set Magnitude = 1
end
end
subsection Material model
set Model name = simple
subsection Simple model
set Reference density = 20
set Reference specific heat = 0.01
set Reference temperature = 0
set Thermal conductivity = 1
set Thermal expansion coefficient = 2.5e-3
set Viscosity = 1e-7
end
end
subsection Formulation
set Formulation = custom
set Mass conservation = incompressible
set Temperature equation = reference density profile
end
subsection Heating model
set List of model names = shear heating, adiabatic heating
#subsection Adiabatic heating
set Use simplified adiabatic heating = true
#end
end
subsection Mesh refinement
set Initial global refinement = 4
set Initial adaptive refinement = 0
set Time steps between mesh refinement = 0
end
subsection Postprocess
set List of postprocessors = velocity statistics, temperature statistics, heat flux statistics, visualization, depth average, viscous dissipation statistics, heating statistics
subsection Visualization
set List of output variables = density, viscosity, strain rate, heat flux map, artificial viscosity, strain rate tensor, vertical heat flux
set Time between graphical output = 0.05
subsection Heat flux map
set Output point wise heat flux = true
end
#set Interpolate output = true
end
subsection Depth average
set Number of zones = 127
set Time between graphical output = 0.05
set List of output variables = temperature, velocity magnitude, adiabatic density
end
end
subsection Solver parameters
set Temperature solver tolerance = 1e-10
end
