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--- userfunctions:iceproperties [2018/10/27 19:01]
tzwinger [General Description]
+++ userfunctions:iceproperties [2018/11/03 12:14] (current)
tzwinger [General Description]
@@ Line 6: / Line 6: @@
 ==== General Description ====
-The aim of these user functions is to provide a Frotran version of the else as MATC functions prescribed material parameters for ice (except for viscosity, which is handled by Glan's flow law).
+The aim of these user functions is to provide a Fortran version of the else as [[tips:thermoprop|MATC functions]] prescribed material parameters for ice (except for viscosity, which is handled by Glen's flow law). Fortran functions are way faster in execution time, which, in a run that repeatedly calls those parameters, can lead to tremendous speed-ups. Hence, if computing thermo-mechanically coupled problems, rather stick to those.
-'IceConductivity'': The heat conductivity of ice as a fcuntion of temperature (<m>T</m>) is defined (in SI units) as:
+All input is expected to be in SI units (Temperature in Kelvin). All outputs by default are in SI units, except the user provides scaling factors (see below).
-<m> kappa_{ice} = 9.828  exp(-5.7^{-3}*T)</m>
+===IceConductivity===
+ The heat conductivity of ice as a function of temperature (<m>T</m>) is defined (in SI units) as:\\
+ <m>\kappa_{ice} = 9.828 . exp(-5.7^{-3} . T) [W m^{−1} K^{−1}]</m>\\
+===IceCapacity===
+ The capacity of ice as a function of temperature (<m>T</m>) is defined (in SI units) as:\\
+ <m>c = 146.3 + (7.253 . T) [J kg^{−1} K^{−1}]</m>\\
+===IcePressureMeltingPoint===
+The pressure melting point of ice as a function of pressure (<m>p</m>) is defined as (in Kelvin):\\
+ <m>T_{pmp} = 273.15 - C_{cc} . max(p, 0) [K]</m>\\
+where <m>C_{cc}</m> is the Clausius Clapeyron constant. In case of negative ice pressures (actually, any below atmospheric pressures), the function uses the reference value at atmospheric pressure.
+==== SIF contents ====
+The required keywords in the SIF file for these user functions are:
+<code>
+$secondsperyear = 365.25 * 24.0 * 3600.0
+Constants
+   Clausius Clapeyron = Real 9.8e-08
+End
+Material 1
+  Name = "ice"
+  ! Heat transfer stuff (converted to MPa-m-a system)
+  Temp Heat Capacity = Variable Temp
+    Real Procedure "ElmerIceUSF" "IceCapacity"
+  Heat Capacity Scaling Factor = Real $(secondsperyear)^(2.0)
+  Temp Heat Conductivity = Variable Temp
+    Real Procedure "ElmerIceUSF" "IceConductivity"
+  Heat Conductivity Scaling Factor = Real $(secondsperyear)*1.0E-06
+  Temp Upper Limit = Variable HydroPressure
+    Real Procedure "ElmerIceUSF" "IcePressureMeltingPoint"
+  Pressure Scaling Factor = Real 1.0E06 ! from MPa to Pa
+End
+</code>
 ==== Examples ====
 An example demonstrating the use of the thermal properties of ice can be found in ''[ELMER_TRUNK]/elmerice/Tests/TemperateIceTestFct''.
+==== References ====
+Ritz, C. 1987. Time dependent boundary conditions for calculation of temperature fields in ice sheets. In: E. D. Waddington and J. S. Walder (Eds.), The Physical Basis of Ice Sheet Modelling, IAHS Publication No. 170, pp. 207–216. IAHS Press, Wallingford, UK.

userfunctions/iceproperties.1540666915.txt.gz · Last modified: 2018/10/27 19:01 by tzwinger

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