Field continuity in comsol 5.3
![field continuity in comsol 5.3 field continuity in comsol 5.3](https://cdn.comsol.com/wordpress/2016/06/Heat-flux-input.png)
In this work we use COMSOL Multiphysics (version 5.3) 22, a commercial finite-element based software package, to model the thermo-viscous effects around a single spherical silica particle ( SiO 2) in water, in a planar acoustic field, using the set-up shown in Fig. These simulations act as a building block for the investigation of the interactions between particles mediated by the shear fields in concentrated or aggregated particle systems.
![field continuity in comsol 5.3 field continuity in comsol 5.3](https://cdn.comsol.com/release/53/semiconductor-module/isfet-tutorial-model.jpg)
Here, we report simulations of the shear wave fields around a single (solid) silica particle with diameter 50 nm to 450 nm in water, and the influence of particle size and frequency on the wave amplitude, wavelength, and viscous dissipation in the region of the particle. We have recently reported simulations of the thermal decay fields around liquid particles in a liquid medium, which lead to thermal interactions between particles in a cluster 21. In order to do this, a detailed description of the amplitude and extent of the decay fields around silica clusters needs to be determined, and this is founded in the single-particle system investigated here. for separation and sorting 17, 18), relies on a thorough understanding of the shear effects occurring in clusters or ensembles of particles in a viscous liquid and their dependence on parameters such as frequency and particle size 19, 20. The characterisation of particulate systems and the application of ultrasonic manipulation to influence particle dynamics (e.g. This is important for understanding the nano- and micro-particle effects in industrial processes 14, biological systems 15, and environmental pollution using ultrasound 16 (to name but a few areas). Thus, we are interested in investigating the shear 1 field around a solid spherical scatterer, such as silica, in a viscous liquid, such as water 1. As concentration increases these decay fields overlap with neighbouring particles, leading to a reduction in the dissipation of energy, and a recombination effect with the compressional wave - meaning less attenuation. It is believed that the reason for this is that consideration of the short-range decay fields produced by the compressional wave at the particle interfaces are commonly neglected 10– 13. However, there remains uncertainty over the accuracy of using this modality because many existing models for evaluation of the spectra overestimate the attenuation found experimentally, particularly as the concentration of particles increases 1, 10. Ultrasonic methods can be employed successfully for characterisation of a sample or product 5– 9. This can happen at very low concentrations, rendering traditional light scattering techniques inadequate 4. of the scatterer is perhaps best evaluated through ultrasonic spectroscopy when the concentration is high enough to make the sample impenetrable by light 1– 3. In the analysis of solid particles in liquids, the size, density, etc. We also compare the numerical modelling to semi-analytical results. Therefore, we examine in detail the velocity, vorticity and viscous dissipation in the shear wave field and around the silica spheres using finite element modelling, giving clarity to the viscous boundary effects. This is important because the overlap of these fields ultimately leads to the conversion of a compressional wave to shear waves and back into the compressional wave, the effect originating due to the density contrast between the particle and the liquid. Herein, we consider silica spheres of 50–450 nm diameter in the long-wavelength regime to elucidate the form of the shear decay fields at the liquid/solid interface for individual particles.
#FIELD CONTINUITY IN COMSOL 5.3 VERIFICATION#
It was recently shown through experimental verification that multiple scattering theory must include shear wave influences at the boundary between the liquid and solid particles in a nanofluid when the concentration of the scatterers is even as low as a few percent by volume. Upon application of ultrasonic waves to a suspension of solid particles in liquid, multiple scattering occurs at the particle/liquid interfaces leading to attenuation.