text: #!/usr/bin/env python2
  # -*- coding: utf-8 -*-
  """
  Created on Fri Nov 16 11:35:00 2018
  
  @author: jennywong
  """
  
  ###############################################################################
  # COREPROPERTIES.PY                                                            #
  ###############################################################################
  
  # Desciption: estimates of the physical properties of the core
  
  # Time
  gigayear = 1e9*365.25*24*60*60; # billion years in seconds
  year = 365.25*24*60*60
  
  # PREM
  icb_radius = 1.2215e6 # ICB radius
  cmb_radius = 3.48e6 # CMB radius
  earth_radius = 6.371e6 # radius of the Earth
  density_melting = 0.024e4 # change in density upon melting (Alfe 2002, ab initio)
  density_solidFe = 1.27e4 # specific density of solid iron
  density_liquidFe = density_solidFe-density_melting # specific density of liquid
  #                                           iron + S/Si (also reference density)
  mass_core=1.94e24 # mass of the core (kg) (Davies, 2015)
  mass_oc=1.84e24 # mass of the outer core (kg) (Davies, 2015)
  density_liquidO = 0.556e4 # specific density of light element (see Gubbins 2004)
  bulk_modulus= 1.324e12 # bulk modulus
  hydrostatic_pressure_gradient = 5.509e4 # assumed constant in steady state
  
  # Change in specfic volume (ideal solution theory)
  # ...between solid and liquid iron
  deltaV_solidFe_liquidFe = 1/density_liquidFe - 1/density_solidFe
  # ...between light element and liquid iron
  deltaV_liquidO_liquidFe = 1/density_liquidO - 1/density_liquidFe
  
  # Gruneisen parameter
  gruneisen=1.51
  
  # Expansion coefficients
  alphaT=1e-05 # thermal
  alphaXi=1.1 # compositional # CHECK
  
  # Core chemistry
  aO=16 # atomic no. of oxygen
  aFe=56 # atomic no. of iron
  aSSi=30 # atomic no. of silicon/sulphur
  
  # Other properties
  heat_capacity=715 # (Jkg^-1K^-1) Gubbins 2003
  latent_heat=0.75e6 # (Jkg^-1)
  self_diffusion= 0.98e-8
  