Open Access

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Marcello Lappa¹
FDMP-Fluid Dynamics & Materials Processing, Vol.1, No.3, pp. 201-212, 2005, DOI:10.3970/fdmp.2005.001.201
Abstract The manuscript deals with a presentation of the most reliable theories introduced over the years to model particle coalescence and non-coalescence phenomena at both macroscopic and microscopic length scales (including historical developments and very recent contributions) and moves through other macrophysical mechanisms that can cause spatial separation of the fluid phases (liquid-liquid or liquid-gas) in multi-material problems, while providing a rigorous theoretical framework for deeper understanding of how drop (or bubble) migration due to gravity and/or Marangoni effects can interact cooperatively with coalescence to significantly affect the multiphase pattern formation, its evolutionary progress as well as the final quality of… More >

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1115

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ARTICLE

Marcello Lappa¹
FDMP-Fluid Dynamics & Materials Processing, Vol.1, No.3, pp. 213-234, 2005, DOI:10.3970/fdmp.2005.001.213
Abstract The physical properties of many emulsions and metal alloys strongly depend on the multiphase morphology which is controlled to a great degree by particle-particle interaction during the related processing. In the present article significant effort is devoted to illustrate the philosophy of modeling for these phenomena and some insights into the physics. Within such a context working numerical techniques that have enjoyed a widespread use over recent years are presented and/or reviewed. Finally a focused and critical comparison of these possible approaches is reported illustrating advantages and disadvantages, strengths and weaknesses, past history and future directions. More >

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1618

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1112

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ARTICLE

P. Yu¹, T. S. Lee¹, Y. Zeng¹, H. T. Low²
FDMP-Fluid Dynamics & Materials Processing, Vol.1, No.3, pp. 235-246, 2005, DOI:10.3970/fdmp.2005.001.235
Abstract A numerical model is developed for the investigation of flow field and mass transport in a micro-bioreactor, of working volume below 5 ml, in which medium mixing is generated by a magnetic stirrer-rod rotating on the bottom. The flow-field results show that a recirculation region exists above the stirrer rod and rotates with it; the related fluid mixing is characterized by a circulation coefficient of up to 0.2 which is about five times smaller than that of a one-litre stirred-tank bioreactor. The oxygen transfer coefficient is less than 5 h^-1 which is two orders smaller than that of a 10-litre… More >

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1302

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ARTICLE

C. Giessler¹, C. Sievert², U. Krieger¹, B. Halbedel¹, D. Huelsenberg¹, U. Luedke², A. Thess^1,2,3
FDMP-Fluid Dynamics & Materials Processing, Vol.1, No.3, pp. 247-266, 2005, DOI:10.3970/fdmp.2005.001.247
Abstract Buoyancy driven motion of a highly viscous electrically conducting fluid under the influence of Lorentz forces is investigated theoretically and experimentally. This problem is relevant to the processing of glass, where it is of considerable interest to know whether electromagnetic forces can effectively improve mixing and help to avoid undesired flow patterns in glass melting furnaces. Two highly simplified models are proposed in which the fluid is assumed to be confined in a circular loop containing several localized resistive heating, convective cooling, and electromagnetic forcing elements. The first model is used to derive the scaling laws of the mean velocity… More >

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1094

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ARTICLE

K. Sefiane¹
FDMP-Fluid Dynamics & Materials Processing, Vol.1, No.3, pp. 267-276, 2005, DOI:10.3970/fdmp.2005.001.267
Abstract In this paper the experimental results on the wetting behaviour of volatile binary sessile drops are reported. The evaporation rate is varied through the control of the ambient total pressure. The dynamic wetting contact angle of an evaporating Water-Ethanol drop is investigated at various sub-atmospheric pressures. The wetting properties (contact angle, shape and volume) are monitored in time using a drop shape analysis instrument. The results show that the evaporation of the binary droplet takes place in two stages: the first stage where the wetting behaviour is very similar to the pure ethanol case and a second stage where the… More >

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