5.4.9 Dust/Molecules/Hydrogen Ionization: General

CO5BOLD can now handle a number of additional density arrays. They can be used to describe e.g. the mass density of dust distribution moments or number densities of molecules. These species are properly advected with the gas density. There is also already a small number of dust/molecule formation models available. These models have to be improved in the future and the influence on the radiation field (opacities, radiation pressure on dust) has to be taken into account.

• character dustscheme:
  A scheme for dust or molecule formation and transport can be selected e.g. with
  character dustscheme f=A80 b=80 n='Dust model' &
    c0='none (default), nosource, dust_simple_01, co_component01_01' &
    c1='dust_k3mon_01, dust_k3mon_02'
  dust_k3mon_01
  
  The following values are currently possible:
  • none, None: No handling of any dust/molecule density at all.
  • nosource: Skip source term step for dust/molecules entirely, but do the transport.
  • dust_simple_01: Simple and unrealistic 'dust' formation model (only for testing of the numerics).
  • co_component01_01: Simple CO formation (from Matthias Steffen) with one component only but realistic time scales.
  • dust_k3mon_01: Simple C-rich dust formation (routines from Susanne Höfner) with one component only but realistic time scales.
  • dust_k3mon_02: Simple C-rich dust formation (routines from Susanne Höfner) with two components for dust density and free carbon density.
  • dust_k3mon_03: Simple Forsterite dust formation (based on routines from Susanne Höfner) with two components for dust density and free "Forsterite monomer" density.
  • dust_bins_01: Multi-size-bin Forsterite dust formation (based on Rossow's equations) with one bin for the monomers and several bins for the different grain sizes.
  • dust_moment04_c2: C-rich dust chemistry, 4 moments (routines from Susanne Höfner).
  • chemreacnet: chemical reaction networks (routines from Sven Wedemeyer-Böhm and Inga Kamp).
  • hiontd: time-dependent hydrogen ionization (routines from Jorrit Leenaarts and Sven Wedemeyer-Böhm).

• character dustreconstruction:
  While usually (i.e., when this parameter is not set) the reconstruction scheme for the additional density fields is the same as for the normal hydrodynamics quantities (see 5.4.7), it can make sense to chose a more aggressive but strictly monotonic scheme for these additional fields. It can be chosen e.g., with
  character dustreconstruction f=A80 b=80 n='Reconstruction method for qucs' &
    c0=Constant c1=Minmod/VanLeer/Superbee c2=PP/PPmimo &
    c3=FRmimo,FRmono
  FRmono
  
  Usuful combinations are
  • reconstruction=vanLeer, dustreconstruction=Superbee.
  • reconstruction=FRweno, dustreconstruction=FRmono.
  • reconstruction=FRweno, dustreconstruction=PP.

• real c_dust0X:
  There are ten parameters ( real c_dust01 to real c_dust10) to control each dust formation scheme in detail. A parameter can be given as in
  real c_dust01 f=E15.8 b=4 n='Dust parameter 1'
  0.0
  
  The meaning (and unit) can vary from scheme to scheme. The default value is 0.0 in each case.
  Important: The parameter real c_dust01 must be set to 1.0 in order to activate advection of particle densities for the CHEM (chemreacnet) and the HION (hiontd) module. The default value is 0.0, i.e. advection is switched off.

• character chem_reacfile:
  The name of the input file containing the chemical reaction network.
  character chem_reacfile f=A80 b=80 n='file name of reaction table'
  chem.dat
  

• character chem_reacpath:
  The path of the input file containing the chemical reaction network.
  character chem_reacpath f=A80 b=80 n='path of reaction table'
  /data/sven/cobold/dat/chem/
  

• real chem_abumetal:
  Abundance of the representative metal ('M', if present) relative to hydrogen ( $\epsilon_\mathrm{M} = [M] / [H]$). A value of 1.0E-04 means there are $10^4$ hydrogen atoms for every metal atom. The metal number density for each grid cell is then derived via $n_\mathrm{H} = \epsilon_\mathrm{M} \rho / m_\mathrm{H}$ (assuming a pure hydrogen gas). This parameter is ignored when a quc array for the metal is found in the input model.
  real chem_abumetal f=E15.8 b=4 n='Chemical abundance of repres. metal'
  1.0E-04
  

• character hion_datapath:
  The path of all input files for HION.
  character hion_datapath f=A80 b=80 n='HION data path'
  /data/sven/cobold/dat/hion/
  

• character hion_atomfile:
  The file name of the model atom for HION.
  character hion_atomfile f=A80 b=80 n='HION atom file name'
  H_6.atom
  

• character hion_abufile:
  The name of the HION input file containing the chemical abundances.
  character hion_abufile f=A80 b=80 n='HION abundance file name'
  abundance.input
  

• character hion_edensfile:
  The name of the HION input file containing the electron density table.
  character hion_edensfile f=A80 b=80 n='HION electron density file name'
  edens.dat
  

• character hion_pffile:
  The name of the HION input file containing the partition functions.
  character hion_pffile f=A80 b=80 n='HION partition function file name'
  pf_kurucz.dat
  

• real dtime_out_hion:
  Time increment for additional HION output. Positive values specify the time increment in seconds, negative values the increment in computational time steps. Setting the parameter to zero, suppresses the output.
  real dtime_out_hion f=E15.8 b=4 n='Output file time step (HION)'
  -10.0
  

• integer hion_chunks:
  Number of chunks to use for HION in order to limit the required memory. Do not make it bigger than the number of points in the x2 direction.
  integer hion_chunks f=I9 b=4 n='Number of HION chunks'
  1