Showing papers on "Schmidt number published in 1974"
TL;DR: In this paper, a wide range of Rayleigh numbers have been used to correlate natural convection transfer coefficients for highly unsymmetrical planforms, which heretofore had not been demonstrated.
Abstract: Natural convection adjacent to horizontal surfaces of circular, square, rectangular, and right triangular planforms has been studied experimentally. Electrochemical techniques were employed involving a fluid with a Schmidt number of about 2200. The results encompass a wide range of Rayleigh numbers thus providing information on both the laminar and the turbulent regimes. The data for all planforms are reduced to a single correlation in the laminar and turbulent regimes using the characteristic length, as recommended by Goldstein, Sparrow, and Jones. L* = A/p, where A is the surface area and p is the surface perimeter. The laminar data for all planforms are correlated by the expression Sh = 0.54 Ra1/4 (2.2 × 104 ≤ Ra ≤ 8 × 106) and the data for the turbulent regime are correlated by the expression Sh = 0.15 Ra1/3 (8 × 106 ≤ 1.6 × 109) Transition is found to occur at about Ra = 8 × 106 . The present work thus significantly extends the Rayleigh number range of validity for the use of L* through the 1/4 power laminar regime into the turbulent 1/3 power regime. It also demonstrates the validity of the use of L* to correlate natural convection transfer coefficients for highly unsymmetrical planforms, which heretofore had not been demonstrated. Comparisons to analytical solutions and other experimental heat and mass transfer data are presented.
297 citations
TL;DR: In this article, experimental measurements of mass transfer in an electrochemical flow cell of rectangular cross section with different hydrodynamic entrance and electrode lengths have been made, and correlations with fully developed flow equations are satisfactory.
56 citations
TL;DR: In this paper, numerical solutions have been found for the vapor density field around a simple ice plate, idealized as an oblate spheroid of axis ratio 0.05, having Reynolds numbers between 0.1 and 20, and failing in a fluid of Schmidt number 0.71.
Abstract: Numerical solutions have been found for the vapor density field around a simple ice plate, idealized as an oblate spheroid of axis ratio 0.05, having Reynolds numbers between 0.1 and 20, and failing in a fluid of Schmidt number 0.71. The present solutions are compared with experimental data after Thorpe and Mason for evaporating ice plates, the numerical results of Masliyah and Epstein for oblate spheroids of axis ratio 0.2, and the analytical results of Brenner for thin disks. It is shown that the ventilation coefficient varies linearly with NSc⅓NRc½ at higher Reynolds numbers, while as the Reynolds number approaches zero it approaches its stationary value via the analytical solution of Brenner. Over the range of Reynolds numbers investigated, ventilation coefficients for thin oblate spheroids were found to be lower than those for spheres.
26 citations
TL;DR: In this paper, the authors measured the radial and tangential eddy diffusivities of mass in a fully developed turbulent flow in a plain circular tube for Schmidt numbers ranging from 760 to 1200 with Reynolds number ranging from 5230 to 23 550.
24 citations
TL;DR: In this paper, the authors defined specific heat and enthalpy of species and the rate of production of species in the presence of specific heat as a function of the species' specific rate constant.
Abstract: Nomenclature Cp = specific heat hi = enthalpy of species i k = specific rate constant L = characteristic length (width of chamber) Pr = Prandtl number Re = Reynolds number Sc = Schmidt number T = temperature V = velocity vector W = molecular weight Yn = concentration of species n yn = mass fraction of species n v = stoichiometric coefficient p = density 4* = stream function Q = vorticity a)n = rate of production of species n
4 citations
TL;DR: In this article, it was shown that at high Prandtl or Schmidt numbers such roughness can markedly increase the coefficients of heat and mass exchange in a surface with slight roughness.
Abstract: Flow over a surface with slight roughness is examined. It is established that at high Prandtl or Schmidt numbers such roughness can markedly increase the coefficients of heat and mass exchange.
3 citations
TL;DR: In this article, the transient equations for longitudinal (along the flow) velocity pulsations and pulsations of concentration in the region of a viscous underlayer are considered, and expressions are obtained for the turbulent viscosity and diffusion coefficients.
Abstract: The transient equations for longitudinal (along the flow) velocity pulsations and pulsations of concentration in the region of a viscous underlayer are considered. Estimates based on experimental data enable the contributions arising from certain terms of these equations to be neglected in turbulent transfer. Subject to this approximation, expressions are obtained for the turbulent viscosity and diffusion coefficients. These coefficients behave differently in the case of large Schmidt (Prandtl) numbers. The behavior of the turbulent Schmidt number in the region of the viscous underlayer is analyzed.
1 citations
01 Jan 1974
TL;DR: In this article, the transient equations for longitudinal (along the flow) velocity pulsations and pulsations of concentration in the region of a viscous underlayer are considered, and expressions are obtained for the turbulent viscosity and diffusion coefficients.
Abstract: The transient equations for longitudinal (along the flow) velocity pulsations and pulsations of concentration in the region of a viscous underlayer are considered. Estimates based on experimental data enable the contributions arising from certain terms of these equations to be neglected in turbulent transfer. Subject to this approximation, expressions are obtained for the turbulent viscosity and diffusion coefficients. These coefficients behave differently in the case of large Schmidt (Prandtl) numbers. The behavior of the turbulent Schmidt number in the region of the viscous underlayer is analyzed.
30 Jan 1974
TL;DR: In this article, the authors defined specific heat and enthalpy of species and the rate of production of species in the presence of specific heat as a function of the species' specific rate constant.
Abstract: Nomenclature Cp = specific heat hi = enthalpy of species i k = specific rate constant L = characteristic length (width of chamber) Pr = Prandtl number Re = Reynolds number Sc = Schmidt number T = temperature V = velocity vector W = molecular weight Yn = concentration of species n yn = mass fraction of species n v = stoichiometric coefficient p = density 4* = stream function Q = vorticity a)n = rate of production of species n