摘要:

Laser Doppler Anemomeiry was used to measure the primary (axial) and secondary (recirculating) velocity profiles in laminar flows of Newtonian (ethylene glycol) and non-Newtonian (aqueous solutions of CMC and PAA) liquids in curved tubes. Rheological characteristics of these liquids were measured using standard viscometric techniques (Haake and Mechanical Spectrometer). The effect of the shear-thinning viscosity is to flatten the axial velocity profile while enhancing the circulating flow close to the walls. On the other hand, the viscoelasticity reduces the extent of the secondary flow for all Dean numbers. This fact explains the reduction of laminar friction reported in the literature.

ISSN:0098-6445    

DOI:10.1080/00986448308940593

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The coupled fluid mechanics and mass transfer problems for the retardation by surfactant of an essentially spherical droplet in creeping flow are solved simultaneously. The mass transfer mechanisms of diffusion in the exterior liquid, surface diffusion, and adsorption kinetics are treated separately. No assumptions are made concerning the form of the velocity profile. The solutions are obtained by collocation methods with Newton iteration. The velocity profile and concentration distribution are improved simultaneously, not alternately. The numerical results reveal as limiting cases the uniformly retarded and stagnant cap interfacial velocity profiles considered previously.

ISSN:0098-6445    

DOI:10.1080/00986448308940594

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Particle deposition from suspensions flowing past bi-sphcre collectors was studied using the conventional trajectory calculations. The collector is composed of two spheres, with the line connecting the two sphere centers coinciding with the direction of the main flow. For the case in which the dominant mechanism of particle collection is interception, the collection efficiency of the bi-sphere is found to be less than that of the single-sphere collector. The reverse holds true when the effect of panicle inertia becomes more pronounced.

ISSN:0098-6445    

DOI:10.1080/00986448308940595

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Weak turbulent mixing processes increase the effective exchange rate of a passive additive between a small element of fluid and its surroundings. An approximate mean Green's function, controlled by molecularandturbulent diffusion, is used to estimate this exchange rate at high Schmidt numbers for a fully-developed turbulent flow near a rigid interface. The calculations show that turbulent mixing decreases the magnitude of the diffusive and retarding contributions to the turbulent flux and that this leads to a net decrease in the mass transfer rate.

ISSN:0098-6445    

DOI:10.1080/00986448308940596

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The deposition of magnetite from flowing water suspensions is a problem particularly important in boiler plant. Measurements have been made of the rate of deposition of magnetite particles from suspension in demincraliscd water pumped through vertical aluminium tubes of 19 mm bore over a range of temperatures I2-75°C and Reynolds number 7900 to 88500 under isothermal conditions. Bulk concentrations of magnetite particles (of the order of 2 μm diameter) were in the range 200-600 ppm.

ISSN:0098-6445    

DOI:10.1080/00986448308940597

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

This paper describes the development of a complete set of continuous, comprehensive correlating equations for the recovery factor, and for the various functions of the velocity field which are required for calculation of heat transfer in the laminar boundary layer regime. These expressions are based on theoretical asymptotes and intermediate numerical values. Asymptotes were derived in the few instances for which they were not already known. Additional numerical values were computed to support the construction of the correlating equation for the recovery factor, but prior computed values were sufficient for the velocity functions.

ISSN:0098-6445    

DOI:10.1080/00986448308940598

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

In the present paper literature evidence on solid catalyzed oxidation reactions has been used to model their observed multipliciiy and instability behaviour. The results indicate that such behaviour could arise purely as a result of interactions among the adsorbed species on the catalyst. A simple mechanism like the Eley-Rideal mechanism, in which only one of the reactant species is adsorbed, has been considered, and it has been shown that instabilities can arise as a result of the adsorption behaviour of this species. The results also indicate that these instabilities are more fundamental since neither the kinetic nor the kinetic-cum-diffusion features of the system arc invoked to explain the dynamic behaviour observed in such systems.

ISSN:0098-6445    

DOI:10.1080/00986448308940599

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor