A general solution of the drag force in packed beds of multi-sized particles under creeping fluid flow conditions

Agglomeration of particulate matter in chimneys using acoustic flow

The emission of micrometer-sized particulate matter on an industrial scale is causing increasing environmental concern about air pollution. Numerous industries and research communities need help to reduce micrometer-sized pollutants in the atmosphere. The current research investigates the acoustic agglomeration of particulate matter through a combination of experimental and numerical methods. Acoustic agglomeration is a process that involves using acoustic waves to influence the movement of particles in the air. Acoustic agglomeration operates by facilitating particle collision and simplifying the formation of agglomerates that are later removed through filtration. This article is focused on research on acoustic pre-processing with the aim of reducing atmospheric pollution caused by toxic combustion products. The capture of fine silica particles with diameters ranging from 0.3 to 10 μm, emitted through the chimneys of industrial enterprises, can be considered a significant technological innovation. The experimental part of the current research is conducted using a newly developed experimental bench. The assembly comprises the following key components: a wind tunnel, a particle dosing device, the agglomeration camera, and a particle concentration measurement device on the edge of the bench. A loudspeaker was used to evaluate the effect of sound pressure in the frequency range of 500-3000 Hz. A comprehensive CFD study of the particles was conducted, which included analysis of the boundary layer, facilitating a better understanding of the behavior of the particles and its potential to agglomerate. An experimental study of particle agglomeration, using an acoustic field with a frequency range of 500-3000 Hz, demonstrated the effectiveness of particle agglomeration of different diameters. The efficacy of particle agglomeration is up to 80 % when the sound pressure values were 129-135 dB; the highest efficiency was found at excitation frequencies of 1500 and 3000 Hz, respectively.

A Simple Approach to Estimate the Drag Coefficients of a Submerged Floater

The calculation of the drag force is a fundamental requirement in the design of any submerged system intended for marine exploration. The calculation can be performed by analytic analysis, numerical modeling, or by a direct calculation performed in a designated testing facility. However, for complex structures and especially those with a non-rigid design, the analytic and numerical analyses are not sufficiently accurate, while the direct calculation is a costly operation. In this paper, we propose a simple approach for how to calculate the drag coefficient in-situ. Aimed specifically at the complex case of elastic objects whose modeling via Computer-Aided Design (CAD) is challenging, our approach evaluates the relation between the object's speed at steady-state and its mass to extract the drag coefficient in any desired direction, the hydro-static force, and, when relevant, also the thruster's force. We demonstrate our approach for the special case of a highly complex elastic-shaped floater that profiles the water column. The analysis of two such floaters in two different sea environments shows accurate evaluation results and supports our claim for robustness. In particular, the simplicity of the approach makes it appealing for any arbitrary shaped object.