From 89f0c0dc87806b4e6e1e14008a0a85f96c1bfabe Mon Sep 17 00:00:00 2001 From: mcgratta Date: Mon, 19 Aug 2024 14:13:25 -0400 Subject: [PATCH] FDS Source: Issue #13306. Add MOLECULAR CONDUCTIVITY output --- Manuals/FDS_User_Guide/FDS_User_Guide.tex | 15 +++++++++++++-- Source/data.f90 | 4 ++++ Source/dump.f90 | 4 ++-- 3 files changed, 19 insertions(+), 4 deletions(-) diff --git a/Manuals/FDS_User_Guide/FDS_User_Guide.tex b/Manuals/FDS_User_Guide/FDS_User_Guide.tex index d8077648d90..66e82b58450 100644 --- a/Manuals/FDS_User_Guide/FDS_User_Guide.tex +++ b/Manuals/FDS_User_Guide/FDS_User_Guide.tex @@ -4468,8 +4468,18 @@ \subsubsection{Specifying a Chemical Formula} \subsubsection{Conductivity} +\label{info:CONDUCTIVITY} + +Gas phase thermal conductivity, $k$, can be specified in one of four ways. First, it can be defined as a constant, {\ct CONDUCTIVITY} (\si{W/(m.K)}), on the {\ct SPEC} line. Second, it can be defined as a function of temperature via the ramp, {\ct RAMP\_K}, on the {\ct SPEC} line. Third, it can be computed by FDS using the parameters {\ct MW} and {\ct PR\_GAS} given on the {\ct SPEC} line (the default value {\ct PR\_GAS} is {\ct PR} given on the {\ct MISC} line). Fourth, it can be computed using the Lennard-Jones potential parameters $\sigma$ ({\ct SIGMALJ}) and $\epsilon/k$ ({\ct EPSILONKLJ}) given on the {\ct SPEC} line. If no inputs are specified, FDS will compute the conductivity using the {\ct MW} and the Lennard-Jones parameters for nitrogen. + +These methods of specifying the thermal conductivity are less important in LES simulations where the effective value is the sum of the molecular value, $k$, and a turbulent component, $k_{\rm t}$: +\be + k_{\rm {\tiny LES}} = k + k_{\rm t} \quad ; \quad k_{\rm t} = \frac{c_p \, \mu_{\rm t}}{\PR_{\rm t}} +\ee +The turbulent visosity, $\mu_{\rm t}$, is a function of the local flow field and grid size. The turbulent Prandtl number, $\PR_{\rm t}$, is a specified constant. The specific heat, $c_p$, is a function of the gas temperature and composition for {\ct SIMULATION\_MODE='LES'}, and it is the constant value of the background gas species at ambient temperature for {\ct 'VLES'} and {\ct 'SVLES'}. + +The gas phase output quantity {\ct 'CONDUCTIVITY'} denotes that which is actually used in the simulation, $k_{\rm {\tiny LES}}$, while {\ct 'MOLECULAR CONDUCTIVITY'} is the molecular value, $k$, only; that is, the actual thermal conductivity of the gas with no turbulent component added. -Conductivity can be specified in one of three ways: it can be defined as a constant using {\ct CONDUCTIVITY} (\si{W/(m.K)}), it can be defined as a temperature vs. specific heat ramp using {\ct RAMP\_K}, or it can be computed by FDS using {\ct MW}, {\ct PR\_GAS} on {\ct SPEC} (default value is {\ct PR} on {\ct MISC}), and the Lennard-Jones potential parameters $\sigma$ ({\ct SIGMALJ}) and $\epsilon/k$ ({\ct EPSILONKLJ}). If no inputs are specified, FDS will compute the conductivity using the {\ct MW} and the Lennard-Jones parameters for nitrogen. \subsubsection{Diffusivity} \label{info:diffusivity} @@ -11223,7 +11233,7 @@ \section{Gas Phase Output Quantities} {\ct CHEMISTRY SUBITERATIONS} & Section~\ref{info:chem_integration} & & D,S \\ \hline {\ct CHI\_R} & Section~\ref{info:CHI_R} & & D,I,S \\ \hline {\ct COMBUSTION EFFICIENCY} & $\delta t/\tau_{\mathrm{mix}}$ & & D,I,P,S \\ \hline -{\ct CONDUCTIVITY} & Thermal conductivity & \si{W/(m.K)} & D,I,P,S \\ \hline +{\ct CONDUCTIVITY} & Section~\ref{info:CONDUCTIVITY} & \si{W/(m.K)} & D,I,P,S \\ \hline {\ct C\_SMAG} & Smagorinsky coefficient & & D,I,P,S \\ \hline {\ct DENSITY}$^1$ & Total or species density & kg/m$^3$ & D,I,P,S \\ \hline {\ct DIFFUSIVE MASS FLUX X}$^1$ & Section~\ref{info:mass_flow} & kg/s/m$^2$ & D,I,P,S \\ \hline @@ -11256,6 +11266,7 @@ \section{Gas Phase Output Quantities} {\ct MAXIMUM VELOCITY ERROR} & Section \ref{info:PRES} & m/s & D \\ \hline {\ct MIXING TIME} & Combustion mixing time, $\tau_{\rm mix}$ & s & D,I,P,S \\ \hline {\ct MIXTURE FRACTION} & $Z$ & kg/kg & D,I,P,S \\ \hline +{\ct MOLECULAR CONDUCTIVITY} & Section~\ref{info:CONDUCTIVITY} & \si{W/(m.K)} & D,I,P,S \\ \hline {\ct MOLECULAR VISCOSITY} & Molecular viscosity, $\mu(\mathbf{Z},T)$ & \si{kg/(m.s)} & D,I,P,S \\ \hline {\ct OPTICAL DENSITY} & Section~\ref{info:visibility} & 1/m & D,I,P,S \\ \hline {\ct ORIENTED VELOCITY}$^5$ & $(u,v,w)\cdot(n_x,n_y,n_z)$ & m/s & D \\ \hline diff --git a/Source/data.f90 b/Source/data.f90 index 243f4277018..bd2ad527bce 100644 --- a/Source/data.f90 +++ b/Source/data.f90 @@ -299,6 +299,10 @@ SUBROUTINE DEFINE_OUTPUT_QUANTITIES OUTPUT_QUANTITY(49)%UNITS = 'kJ/m3' OUTPUT_QUANTITY(49)%SHORT_NAME = 'H_s' +OUTPUT_QUANTITY(50)%NAME = 'MOLECULAR CONDUCTIVITY' +OUTPUT_QUANTITY(50)%UNITS = 'W/m/K' +OUTPUT_QUANTITY(50)%SHORT_NAME = 'k' + OUTPUT_QUANTITY(51)%NAME = 'RESOLVED KINETIC ENERGY' OUTPUT_QUANTITY(51)%UNITS = 'm2/s2' OUTPUT_QUANTITY(51)%SHORT_NAME = 'k_res' diff --git a/Source/dump.f90 b/Source/dump.f90 index 1dbcaf8d31b..a1a506ea107 100644 --- a/Source/dump.f90 +++ b/Source/dump.f90 @@ -7219,8 +7219,8 @@ REAL(EB) RECURSIVE FUNCTION GAS_PHASE_OUTPUT(T,DT,NM,II,JJ,KK,IND,IND2,Y_INDEX,Z V(II,JJ,KK)*ORIENTATION_VECTOR(2,DV%ORIENTATION_INDEX) + & W(II,JJ,KK)*ORIENTATION_VECTOR(3,DV%ORIENTATION_INDEX) - CASE(33) ! CONDUCTIVITY - IF (SIM_MODE==DNS_MODE) THEN + CASE(33,50) ! CONDUCTIVITY, MOLECULAR CONDUCTIVITY + IF (SIM_MODE==DNS_MODE .OR. IND==50) THEN ZZ_GET(1:N_TRACKED_SPECIES) = ZZ(II,JJ,KK,1:N_TRACKED_SPECIES) CALL GET_CONDUCTIVITY(ZZ_GET,GAS_PHASE_OUTPUT_RES,TMP(II,JJ,KK)) ELSE