% Tutorial 6: Transport properties % % Topics: % - mixture-averaged and multicomponent models % - viscosity % - thermal conductivity % - binary diffusion coefficients % - mixture-averaged diffusion coefficients % - multicomponent diffusion coefficients % - thermal diffusion coefficients % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % Methods are provided to compute transport properties. By % default, calculation of transport properties is not enabled. If % transport properties are required, the transport model must be % specified when the gas mixture object is constructed. % Currently, two models are implemented. Both are based on kinetic % theory expressions, and follow the approach described in Dixon-Lewis % (1968) and Kee, Coltrin, and Glarborg (2003). The first is a full % multicomponent formulation, and the second is a simplification that % uses expressions derived for mixtures with a small number of species % (1 to 3), using approximate mixture rules to average over % composition. % To use the multicomponent model with GRI-Mech 3.0, call function % GRI30 as follows: g1 = GRI30('Multi') % To use the mixture-averaged model: g2 = GRI30('Mix') % Both models use a mixture-averaged formulation for the viscosity. visc = [viscosity(g1), viscosity(g2)] % The thermal conductivity differs, however. lambda = [thermalConductivity(g1), thermalConductivity(g2)] % Binary diffusion coefficients bdiff1 = binDiffCoeffs(g1) bdiff2 = binDiffCoeffs(g2) % Mixture-averaged diffusion coefficients. For convenience, the % multicomponent model implements mixture-averaged diffusion % coefficients too. dmix2 = mixDiffCoeffs(g1) dmix1 = mixDiffCoeffs(g2) % Multicomponent diffusion coefficients. These are only implemented % if the multicomponent model is used. dmulti = multiDiffCoeffs(g1) % Thermal diffusion coefficients. These are only implemented with the % multicomponent model. These will be very close to zero, since % the composition is pure H2. dt = thermalDiffCoeffs(g1) % Now change the composition and re-evaluate set(g1,'X',ones(nSpecies(g1),1)); dt = thermalDiffCoeffs(g1) % Note that there are no singularities for pure gases. This is % because a very small positive value is added to all mole % fractions for the purpose of computing transport properties. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% clear all cleanup