IMPORTANT NOTE: If your system is periodic in the direction of the +heat flux, then the flux is going in 2 directions. This means the +effective heat flux in one direction is reduced by a factor of 2. You +will see this in the equations for thermal conductivity (kappa) in the +Muller-Plathe paper. LAMMPS is simply tallying kinetic energy which +does not account for whether or not your system is periodic; you must +use the value appropriately to yield a kappa for your system.
IMPORTANT NOTE: After equilibration, if the temperature gradient you observe is not linear, then you are likely swapping energy too diff --git a/doc/fix_thermal_conductivity.txt b/doc/fix_thermal_conductivity.txt index 19fa15be33..653f02e929 100644 --- a/doc/fix_thermal_conductivity.txt +++ b/doc/fix_thermal_conductivity.txt @@ -81,9 +81,17 @@ As described below, the total kinetic energy transferred by these swaps is computed by the fix and can be output. Dividing this quantity by time and the cross-sectional area of the simulation box yields a heat flux. The ratio of heat flux to the slope of the -temperature profile is the thermal conductivity of the fluid, -in appopriate units. See the "Muller-Plathe paper"_#Muller-Plathe for -details. +temperature profile is proportional to the thermal conductivity of the +fluid, in appropriate units. See the "Muller-Plathe +paper"_#Muller-Plathe for details. + +IMPORTANT NOTE: If your system is periodic in the direction of the +heat flux, then the flux is going in 2 directions. This means the +effective heat flux in one direction is reduced by a factor of 2. You +will see this in the equations for thermal conductivity (kappa) in the +Muller-Plathe paper. LAMMPS is simply tallying kinetic energy which +does not account for whether or not your system is periodic; you must +use the value appropriately to yield a kappa for your system. IMPORTANT NOTE: After equilibration, if the temperature gradient you observe is not linear, then you are likely swapping energy too diff --git a/doc/fix_viscosity.html b/doc/fix_viscosity.html index 57e0502b30..5b59cb1cbf 100644 --- a/doc/fix_viscosity.html +++ b/doc/fix_viscosity.html @@ -92,9 +92,17 @@ sense. This is why Nbin is restricted to being an even number. swaps is computed by the fix and can be output. Dividing this quantity by time and the cross-sectional area of the simulation box yields a momentum flux. The ratio of momentum flux to the slope of -the shear velocity profile is the viscosity of the fluid, in -appopriate units. See the Muller-Plathe paper for -details. +the shear velocity profile is proportional to the viscosity of the +fluid, in appropriate units. See the Muller-Plathe +paper for details. +
+IMPORTANT NOTE: If your system is periodic in the direction of the +momentum flux, then the flux is going in 2 directions. This means the +effective momentum flux in one direction is reduced by a factor of 2. +You will see this in the equations for viscosity in the Muller-Plathe +paper. LAMMPS is simply tallying momentum which does not account for +whether or not your system is periodic; you must use the value +appropriately to yield a viscosity for your system.
IMPORTANT NOTE: After equilibration, if the velocity profile you observe is not linear, then you are likely swapping momentum too diff --git a/doc/fix_viscosity.txt b/doc/fix_viscosity.txt index 511c194bbb..8f2fe13810 100644 --- a/doc/fix_viscosity.txt +++ b/doc/fix_viscosity.txt @@ -81,9 +81,17 @@ As described below, the total momentum transferred by these velocity swaps is computed by the fix and can be output. Dividing this quantity by time and the cross-sectional area of the simulation box yields a momentum flux. The ratio of momentum flux to the slope of -the shear velocity profile is the viscosity of the fluid, in -appopriate units. See the "Muller-Plathe paper"_#Muller-Plathe for -details. +the shear velocity profile is proportional to the viscosity of the +fluid, in appropriate units. See the "Muller-Plathe +paper"_#Muller-Plathe for details. + +IMPORTANT NOTE: If your system is periodic in the direction of the +momentum flux, then the flux is going in 2 directions. This means the +effective momentum flux in one direction is reduced by a factor of 2. +You will see this in the equations for viscosity in the Muller-Plathe +paper. LAMMPS is simply tallying momentum which does not account for +whether or not your system is periodic; you must use the value +appropriately to yield a viscosity for your system. IMPORTANT NOTE: After equilibration, if the velocity profile you observe is not linear, then you are likely swapping momentum too