Author
Steven P. Trainoff
Bio: Steven P. Trainoff is an academic researcher. The author has contributed to research in topics: Shadowgraph & Multiangle light scattering. The author has an hindex of 2, co-authored 4 publications receiving 228 citations.
Papers
More filters
TL;DR: In this article, the authors review the history of experimental work on Rayleigh-Benard convection in gases, and then describe a modern apparatus that has been used in their experiments on gas convection.
Abstract: We review the history of experimental work on Rayleigh–Benard convection in gases, and then describe a modern apparatus that has been used in our experiments on gas convection. This system allows for the study of patterns in a cell with an aspect ratio (cell radius/fluid layer depth) as large as 100, with the cell thickness uniform to a fraction of a μm, and with the pressure controlled at the level of one part in 105. This level of control can yield a stability of the critical temperature difference for the convective onset of better than one part in 104. The convection patterns are visualized and the temperature field can be inferred using the shadowgraph technique. We describe the flow visualization and image processing necessary for this. Some interesting results obtained with the system are briefly summarized.
118 citations
TL;DR: In this article, the authors present an analysis of the shadowgraph method of visualizing convective flows based on physical optics, treating the refractive-index perturbation caused by the flow as a transmission grating.
Abstract: We present an analysis of the shadowgraph method of visualizing convective flows based on physical optics, treating the refractive-index perturbation caused by the flow as a transmission grating. Various patterns in thermal convection of an isotropic fluid as well as normal rolls in electroconvection of a nematic liquid crystal are considered. The results differ significantly from those of geometrical optics, showing that use of the shadowgraph as a quantitative tool for amplitude measurements should not, in general, be based on geometrical optics.
118 citations
Patent•
02 Feb 2021
TL;DR: In this article, one or more homogenizing elements are employed in a flow-through, multi-detector optical measurement system to correct for problems common to multidimensional optical measurement systems such as peak tailing and non-uniform sample profile within the measurement cell.
Abstract: One or more homogenizing elements are employed in a flow through, multi-detector optical measurement system. The homogenizing elements correct for problems common to multi-detector flow-through systems such as peak tailing and non-uniform sample profile within the measurement cell. The homogenizing elements include coiled inlet tubing, a flow distributor near the inlet of the cell, and a flow distributor at the outlet of the cell. This homogenization of the sample mimics plug flow within the measurement cell and enables each detector to view the same sample composition in each individual corresponding viewed sample volume. This system is particularly beneficial when performing multiangle light scattering (MALS) measurements of narrow chromatographic peaks such as those produced by ultra-high pressure liquid chromatography (UHPLC).
Patent•
21 Sep 2016
TL;DR: In this paper, one or more homogenizing elements are employed in a flow-through, multi-detector optical measurement system to correct for problems common to multidimensional optical measurement systems such as peak tailing and non-uniform sample profile within the measurement cell.
Abstract: One or more homogenizing elements are employed in a flow through, multi-detector optical measurement system. The homogenizing elements correct for problems common to multi-detector flow-through systems such as peak tailing and non-uniform sample profile within the measurement cell. The homogenizing elements include coiled inlet tubing, a flow distributor near the inlet of the cell, and a flow distributor at the outlet of the cell. This homogenization of the sample mimics plug flow within the measurement cell and enables each detector to view the same sample composition in each individual corresponding viewed sample volume. This system is particularly beneficial when performing multiangle light scattering (MALS) measurements of narrow chromatographic peaks such as those produced by ultra-high pressure liquid chromatography (UHPLC).
Cited by
More filters
TL;DR: In this article, a review summarizes results for Rayleigh-Benard convection that have been obtained over the past decade or so, focusing on convection in compressed gases and gas mixtures with Prandtl numbers near one and smaller.
Abstract: ▪ Abstract This review summarizes results for Rayleigh-Benard convection that have been obtained over the past decade or so. It concentrates on convection in compressed gases and gas mixtures with Prandtl numbers near one and smaller. In addition to the classical problem of a horizontal stationary fluid layer heated from below, it also briefly covers convection in such a layer with rotation about a vertical axis, with inclination, and with modulation of the vertical acceleration.
823 citations
25 Jun 2015
TL;DR: In this article, the authors consider the interaction between a Particle of Immobile Surface Interacting with a Solid Wall 5.5.2 and Fluid Particles and Films of Tangentially Mobile Surfaces.
Abstract: 5.5 HYDRODYNAMIC INTERACTIONS IN DISPERSIONS 106 5.5.1 Basic Equations. Lubrication Approximation 5.5.2 Interaction Between Particles of Tangentially Immobile Surfaces 5.5.2.1 Taylor and Reynolds Equations, and Influence of the Particle Shape 5.5.2.2 Interactions Among Non-Deformable Particles at Large Distances 5.5.2.3 Stages of Thinning of a Liquid Film 5.5.2.4 Dependence of Emulsion Stability on the Droplet Size 5.5.3 Effect of Surface Mobility 5.5.3.1 Diffusive and Convective Fluxes at an Interface; Marangoni Effect 5.5.3.2 Fluid Particles and Films of Tangentially Mobile Surfaces 5.5.3.3 Bancroft Rule for Emulsions 5.5.3.4 Demulsification and Defoaming 5.5.4 Interactions in Non-Preequilibrated Emulsions 5.5.4.1 Surfactant Transfer from Continuous to Disperse Phase (Cyclic Dimpling) 5.5.4.2 Surfactant Transfer form Disperse to Continuous Phase (Osmotic Swelling) 5.5.4.3 Equilibration of Two Droplets Across a Thin Film 5.5.5 Hydrodynamic Interaction of a Particle with an Interface 5.5.5.1 Particle of Immobile Surface Interacting with a Solid Wall 5.5.5.2 Fluid Particles of Mobile Surfaces 5.5.6 Bulk Rheology of Dispersions
141 citations
TL;DR: A theoretical model for microscope imaging is derived that accounts for the three-dimensional nature of the sample, the arbitrary coherence properties of the light source, and the effect of the finite numerical aperture of the microscope objective and extends to the class of microscopy techniques that can be described by a linear space-invariant imaging of the density of the scattering centers, which includes, for example, dynamic fluorescence microscopy.
Abstract: We describe the use of a bright-field microscope for dynamic light scattering experiments on weakly scattering samples. The method is based on collecting a time sequence of microscope images and analyzing them in the Fourier space to extract the characteristic time constants as a function of the scattering wave vector. We derive a theoretical model for microscope imaging that accounts for (a) the three-dimensional nature of the sample, (b) the arbitrary coherence properties of the light source, and (c) the effect of the finite numerical aperture of the microscope objective. The model is tested successfully against experiments performed on a colloidal dispersion of small spheres in water, by means of the recently introduced differential dynamic microscopy technique [R. Cerbino and V. Trappe, Phys. Rev. Lett. 100, 188102 (2008)]. Finally, we extend our model to the class of microscopy techniques that can be described by a linear space-invariant imaging of the density of the scattering centers, which includes, for example, dynamic fluorescence microscopy.
132 citations