Interfacial turbulence in falling liquid films

下降液膜中的界面湍流

基本信息

批准号：
EP/F016492/1
负责人：
Serafim Kalliadasis
金额：
$ 20.05万
依托单位：
Imperial College London
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2008
资助国家：
英国
起止时间：
2008 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FF016492%2F1
关键词：
Interfacial turbulence falling liquid films

项目摘要

A falling film is a convectively unstable open-flow hydrodynamic system with a rich variety of spatial/temporal structures and a sequence of wave instabilities and transitions which are generic to a large class of hydrodynamic and other nonlinear systems: white noise at the inlet, filtering mechanism of linear instability, secondary modulation that transforms the primary wave field into two-dimensional (2D -- 1+1 dimensions) solitary pulses and eventually transition of the 2D pulses into a fully developed three-dimensional (3D -- 2+1 dimensions) wave regime. This stage of the evolution is frequently referred to as `interfacial turbulence'. This is low-dimensional spatio-temporal chaos or alternatively `weak/dissipative turbulence': indeed, despite the apparent complexity of the system one can still identify 3D solitary pulses in what appears to be a randomly disturbed surface. 3D pulses then become elementary processes so that the dynamics of the film can be described as a superposition of these pulses. Hence, a falling liquid film can serve as a canonical reference system for the study of weak/dissipative turbulence.In addition to the purely theoretical interest, falling liquid films play a central role in the development of efficient means of heat and mass transfer in a wide variety of engineering and technological applications, such as evaporators, heat exchangers, absorbers, scrubbers, rectification columns, crystallizers and falling film reactors. This is mainly due to the small heat and mass transfer resistance of a falling film at relatively small flow rates. This resistance is further decreased by the presence of 2D/3D solitary pulses at the free surface of the film mentioned earlier which typically lead to a significant enhancement of heat and mass transfer.Not surprisingly, therefore, falling liquid films have been a topic of fundamental and applied research for several decades. However,despite the several developments and considerable attention that wave evolution on a falling film has received, a large number of issues and problems have not been resolved, and in particular, the interaction of 3D solitary pulses and eventual transition to interfacial turbulence, still elude us. In an attempt to answer these questions, the field of research to be pursued during the tenure of this project concerns the theoretical development of a coherent structures theory of 3D solitary pulses on a falling film with the principal aim to advance our understanding of interfacial turbulence.

A falling film is a convectively unstable open-flow hydrodynamic system with a rich variety of spatial/temporal structures and a sequence of wave instabilities and transitions which are generic to a large class of hydrodynamic and other nonlinear systems: white noise at the inlet, filtering mechanism of linear instability, secondary modulation that transforms the primary wave field into two-dimensional (2D -- 1+1 dimensions) solitary pulses and eventually 2D脉冲转变为完全开发的三维（3D-2+1维）波状态。进化的这一阶段通常称为“界面湍流”。这是低维时空的混乱或“弱/耗散性湍流”：确实，尽管系统的明显复杂性仍然可以识别出3D孤立的脉冲，但似乎是随机干扰的表面。然后，3D脉冲成为基本过程，因此可以将膜的动力学描述为这些脉冲的叠加。 Hence, a falling liquid film can serve as a canonical reference system for the study of weak/dissipative turbulence.In addition to the purely theoretical interest, falling liquid films play a central role in the development of efficient means of heat and mass transfer in a wide variety of engineering and technological applications, such as evaporators, heat exchangers, absorbers, scrubbers, rectification columns, crystallizers and falling film reactors.这主要是由于以相对较小的流速为掉落的膜的热量和传质电阻较小。在前面提到的膜的自由表面上存在2D/3D孤立脉冲，这通常会导致热量和传质的显着增强。因此，掉落的液体膜一直是基本和应用研究的话题。然而，尽管已经收到了一些波动对落下膜的发展，但尚未解决大量问题和问题，尤其是3D孤立脉冲的相互作用以及最终向界面湍流的过渡，仍然避免了我们。为了回答这些问题，在该项目任期期间要进行的研究领域涉及3D孤立脉冲的一致结构理论的理论发展，其主要目的是促进我们对界面湍流的理解。