Hi ASPECT,

Probably a basic question (I’m pretty new to ASPECT), but I’m looking at some unintuitive results that I think could be clarified quite quickly…

So I’ve run a simple isoviscous calculation with fixed T BCs in a 2D annulus to 1 billion years. At the end, I’m just wondering why, within the convective cells, the temperature is hot in the top half of the mantle and cold in the bottom half… rather than nearly isothermal (or, increasing, adiabatically with depth).

I’ve attached a screenshot (at 1 Gy). IThe parameters I’ve provided in the prm file (pasted below) include compressibility and expansion (so figured that the simulation would be adiabatic?).

I guess I have two basic Qs: is my weird result due to the calculation *not* being compressible?

And also, how would I adapt my parameter file to include it. I recently found the following input options: “Subsection”: Adiabatic conditions model: Parameter: “compute profile”.

Any help appreciated!

Thanks,

Harriet

PARAM file:

# ============================================================

# TEMPLATE FOR MULTIPLE RUNS WHERE WE SWITCH INPUT PARAMTERS

# DEPENDING ON MANAR’S RUNS.

# Options to be switched out will be labeled “SWITCH”

# in comment line above

# ============================================================

# ============================================================

# GLOBAL INPUTS:

set Dimension = 2

set Use years in output instead of seconds = true

set End time = 1e9

# SWITCH

set Output directory = /oscar/data/hclau/hclau/out_0.0-1e23

# ============================================================

# ============================================================

# GRID OPTIONS:

subsection Geometry model

set Model name = spherical shell

subsection Spherical shell

set Inner radius = 3480000

set Outer radius = 6371000

set Opening angle = 360

end

end

subsection Mesh refinement

set Initial global refinement = 6

set Initial adaptive refinement = 0

set Time steps between mesh refinement = 0

end

# ============================================================

# ============================================================

# MODEL PARAMETERS:

subsection Gravity model

set Model name = radial constant

subsection Radial constant

set Magnitude = 9.81

end

end

# SWITCH

subsection Material model

set Model name = depth dependent

subsection Depth dependent model

set Base model = simple

set Depth dependence method = File

set Data directory = /users/hclau/TPW/viscosity/

set Viscosity depth file = visc_0.0-1e23.dat

set Reference viscosity = 1e23

end

subsection Simple model

set Reference density = 4500

set Thermal expansion coefficient = 2.5e-5

set Viscosity = 1e23

set Reference specific heat = 1000

set Thermal conductivity = 4

end

end

# ============================================================

# ============================================================

# remove rotation

subsection Nullspace removal

set Remove nullspace = net rotation

end

# ============================================================

# INITIAL CONDITIONS

# SWITCH

# ATTEMPt 1:

#subsection Initial temperature model

# set Model name = function

# subsection Function

# set Coordinate system = spherical

# set Variable names = r,phi

# set Function constants = A=100, B=75, C=50, D=25, pi=3.1415926536, Ri=3480e3, Ro=6371e3, Ti=5500, To=1700

# set Function expression = (r-Ri)/(Ro-Ri)*(To-Ti)+Ti + A*sin(7*phi) + B*sin(13*phi) + C*cos(0.123*phi+pi/3) + D*cos(0.456*phi+pi/6)

# end

#end

# ATTEMPT 2:

subsection Initial temperature model

set Model name = spherical gaussian perturbation

subsection Spherical gaussian perturbation

set Amplitude = 0.01

set Angle = 0.8

set Non-dimensional depth = 0.2

set Sigma = 0.2

set Sign = 1

end

end

# ============================================================

# ============================================================

# BOUNDARY CONDITIONS

subsection Boundary velocity model

set Zero velocity boundary indicators =

set Tangential velocity boundary indicators = top, bottom

end

# SWITCH ,

subsection Boundary temperature model

set Fixed temperature boundary indicators = top,bottom

set List of model names = spherical constant

subsection Spherical constant

set Inner temperature = 5000

set Outer temperature = 1600

end

end

# SWITCH

#subsection Heating model

# set List of model names = constant heating

# subsection Constant heating

# set Radiogenic heating rate = 1.95e-11

# end

#end

# ============================================================

# ============================================================

# OUTPUT

subsection Postprocess

set List of postprocessors = velocity statistics, temperature statistics, heat flux statistics, visualization, particles, basic statistics

subsection Visualization

set Time between graphical output = 1e6

set Output format = vtu

set List of output variables = material properties

end

end