Disturbances in stratified fluids and solids

分层流体和固体中的干扰

• 批准号: 9117-2011
• 负责人: Seymour, Brian
• 金额: $ 0.8万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=568644
• 关键词: Disturbances; stratified; fluids; solids

Predicting the movement of a disturbance in a fluid or solid whose properties vary rapidly poses considerably more of a challenge than the equivalent problem in homogeneous materials. The inhomogeneities can arise through changes in geometry or of material properties. A combination of perturbation and numerical techniques will be used to investigate a variety of propagation problems in strongly stratified materials. These include high-pressure acoustic oscillations, flows in coastal aquifers, disturbances in functionally graded materials, and the evolution of Kelvin-Helmholtz (KH) instabilities. There has been interest recently in producing high-pressure shockless oscillations of gasses in specially shaped containers. With no shocks, higher pressures result for the same energy input. In explaining this phenomenon, the challenge is to understand the interaction of geometry, stratification and nonlinearity. The intent is to extend these concepts to problems with different geometries and boundary conditions. Coastal aquifers have a dynamic seaward boundary at the coastline that is influenced by oceanic water level fluctuations. The dynamics of these groundwater flows are important for erosion and saltwater intrusion. Natural variations in properties such as hydraulic conductivity and soil porosity mean that the full equations describing flows in aquifers contain variable coefficients. This will be the first systematic attempt to understand the effects of large inhomogeneities on tidal propagation in coastal aquifers. Materials with continuously varying spatial properties are termed functionally graded materials. Our investigation will consider the effects of material inhomogeneities on diffusion and wave-like problems. For wave problems the effect of nonlinearity has the potential to produce shocks. The effects of the stratification and whether different forms of strong stratification can inhibit shocks formation can then be examined. The evolution of KH instabilities at different stages of their life cycle will be examined for Prandtl and Reynolds numbers varying over three decades. Simulation of KH instabilities with Prandtl numbers representing the salinity stratification in the ocean will be considered for the first time.

在性质变化迅速的流体或固体中，预测扰动的运动比在均匀材料中预测等效问题要困难得多。不均匀性可由几何形状或材料性质的变化引起。微扰和数值技术的结合将用于研究强分层材料中的各种传播问题。其中包括高压声波振荡、沿海含水层的流动、功能梯度材料的扰动以及开尔文-亥姆霍兹（KH）不稳定性的演变。