Cinematic viscosity

When the transport is considered without turbulence we have, in general, Dj- u is the cinematic viscosity for the momentum transport a = A,/(pCp) is the thermal diffusivity and D is the diffusion coefficient of species A. Whereas with turbulence we have, in general, Dj-, w, is the cinematic turbulence viscosity for the momentum transport a, =, /(pCp) is the thermal turbulence diffusivity and D t is the coefficient of turbulent diffusion of species A frequently = a = D t due to the hydrodynamic origin of the turbulence. 

Using the cylindrical coordinates (x, r, ), the axial velocity along the centerline is denoted by u, and the mean velocity leaving the nozzle is Ug. The flow is completely defined by Ug, d, and v, cinematic viscosity and hence the only dimensionless parameter is the Reynolds number defined by Re = Ugd/v. In this case the other velocity components, namely radial v and tangential w doesn t exist. 

The chemical passivation of a rotating stainless steel cylinder immersed in an acidic solution is studied as Fe ions are gradually added to the solution. The Fe " ions are reduced to Fe " " at the limiting current as the metal corrodes. The radius of the cylinder is 2 cm, and the rotation rate is 1000 rpm. The diffusion coefficient of the Fe " ions is equal to 0.7 x 10 cm s the cinematic viscosity of the solution is v = 0.011 cm s In the absence of Fe , the anodic polarization curve indicates a passivation current density of L = 30 mA cm , independent of the rotation rate. Calculate the concentration of Fe " " required to passivate the alloy. 

Transport data Cinematic viscosity v (related to the density as dynamic viscosity ri), thermal conductivity 1, and diffusivity D. 

The Archimedes number quotes the ratio of the gravity force and the inertial force in a fluid flow. Thus, high values Ar 1 indicate the applicability of correlations valid for free convection, whereas Arusing equations for forced convection. The intermediate region is characterized by forced convection with superposed free convection. This type of mixed convection often occurs in high-pressure processes, particularly in gas flow due to high Grashof numbers at low cinematic viscosities and enhanced gas densities. The calculation of the summarized heat transfer is possible by the established equation [42] ... 

Like free convective heat transfer, the mass transport in gases is supported by free convection due to the very low cinematic viscosity data at high pressures. 

The critical drop si to sweep with the gas flow as a fimction of the gas capacity factor at different liquid cinematic viscosity and density are presented in Fig. 51 [1]. 

Fig. SI. Critical drop size 4r to sweep with gas flow as a fljnction of gas capacity factor at dififeieat liquid cinematic viscosity and density [1].

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