OpenFOAM implementation for the study of streamwise vortex-induced vibration-based energy harvester for sensor networks

The study of streamwise vortex induced vibration has reached a level of maturity that allows it to be harnessed to generate power. However, studies have primarily concentrated on the variables that measured through point-based instruments. This severely limits our understanding of the fluid forcing mechanism that results in the vibration of the elastically supported bluff body. We proposed the usage of computational fluid dynamics: the open source C++ libraries of OpenFOAM. To implement this successfully to the streamwise vortex-induced vibration problem, which involves near-wall fluid-structure interaction, we explored the method of dynamic mesh handling in OpenFOAM for six degrees of freedom motion of a rigid body fully submerged in fluid. Finally, we argued for the usage of arbitrarily coupled mesh interface to overcome the problem of severely distorted mesh in tight gaps between two walls. We run a short simulation to test this setup and found that the case runs uninterrupted, unlike its former counterpart that relies solely on cell displacement diffusion, suggesting the potential success of a further converged solution of the setup when running on a more powerful machine

HDDs with Better Heat Dissipation Systems Designed for Search Engines Servers

The usage of search engines such as Google, Yahoo and Bing for information seeking is inevitable and important for our daily lives. Google claims that users conduct over a billion searches a day, not including numerous downloads and queries. These search engines have hard disk drives (HDDs) as their core part for data storage. HDDs operating on average 7,200 rotation per minute (rpm) are the norm. However, high-end HDDs meant for fast responses and feedbacks require higher rotational speed and higher track density. These type of HDDs simultaneously need smart countermeasures for excessive heat rise; HDDs’ flow-induced vibration (FIV) such as arm vibrations and disk flutters, without increasing its power consumptions. Gigantic search engines or even cloud computing servers used in nowadays smart computing actually involve numerous HDDs to store these data and information for our convenience. By decreasing the heat generated by these vital core parts of the servers; the HDDs, the authors aim at a lesser energy consumption HDD. Out of the total energy consumed by these servers, only 40 to 45 percent are being used for operation. The remaining energy is consumed for cooling the server and database systems. In this paper, the authors propose a new actuator arm with a better window that will improve the heat dissipation of the HDDs system. The HDD’s actuator arm is designed using AutoDesk and exported to Comsol Multiphysics for numerical simulation. Each arm has a large windowed area for a better dissipation of heat generated due to air frictions. Another improvement that the authors proposed is by designing a novel S-shaped arm to promote better air flow. This will eventually lead to less heat generating HDDs meant for search engines servers of the internet

Numerical Simulation of Drying Process within a Novel Rotary Drying Machine for Palm Oil Sludge

This study investigated how to model a centre-offset annular rotary drum using OpenFOAM and the meshing software GMSH. The diameter of the outer cylinder is 600 mm, diameter of the inner cylinder 200 mm, the centre-offset mm, and rotation rate rpm. When the centre-offset is zero, the quality of mesh is preserved as the drum rotates. Introduction of the offset causes the mesh to be deformed to the point of being unusable as the drum is rotated. The reason was found to be the fixed nodes adjacent to the walls of the outer and inner cylinder. These nodes only respect the motion of the wall they are adjacent to. To circumvent this, we separated the inner volume of the rotary drum to allow the implementation of an OpenFOAM dynamic mesh handling scheme called arbitrary mesh interface (AMI). Implementing AMI allows the quality of the mesh to be kept even when the inner cylinder is rotating under nonzero-offset conditions. This is because AMI permits the sliding of non-conforming meshes next to each other. This preserves the quality of the mesh and secures a reliable and reproducible dynamic mesh motion for the implementation of the drying process in the future

Energy harvesting by exploiting vortex-induced vibration from a modified cruciform structure

From off-grid charging of electronic devices to energising independent wireless sensor networks, the demand for stand-alone, low-power generators from renewable energy sources is becoming more prevalent. A cruciform energy harvester has been shown to output consistent power in the order of 1 mW when the reduced velocity U*, exceeds 15. However, this output is insufficient and its onset too late for realworld applications. Thus, this study seeks to remedy these two shortcomings by investigating cruciforms oscillators at various cruciform angles. To fulfill these goals, the Reynolds-Averaged Navier-Stokes simulation were performed, and the results for the 90° cruciform were compared against experimental data for validation. The experiment uses a similar 90° cruciform in an open flow channel. Assessments were made on the vibration amplitude, frequency, lift amplitude and lift frequency at cruciform angles 90°, 67.5°, 45°, 22.5° and 0°. The Reynolds number range was 1.1x103 Re ≤ 14.6x103 and Scruton number 9.94, which was consistent with similar studies. Hilbert-Huang analysis of the 90° cruciform indicated that a lot of energy from the free stream was wasted in the production of non-performing Karman vortices. A larger lift was possible if streamwise vortices were produced instead. When 45 ≤ a(°) ≤ 67.5, asymmetries in the vortical structures prevented high-amplitude vibrations from taking place. However, when 0 ≤ (°) ≤ 22.5, a high-degree of symmetry among the vortical structures led to an early onset of high-amplitude vibration. Power generated by the cruciform was in the order of 1 mW for a 90° cruciform, below 1m Wwhen 45 ≤ a(°) ≤ 67.5, and in the order of 10 mW when 0 ≤ a(°) ≤ 22.5. Unification of the power generation and energy harvesting efficiency results produced a map that describes the power and efficiency of the harvester in the a(°)-U* parameter space. This uncovers three distinct regions of power generation: pure cruciform region as cruciform angle tends to 90°, steep-angle region between 45 ≤ a(°) ≤ 67.5, and shallow-angle region between 0 ≤ a(°) ≤ 22.5. Maximum efficiency occurs close to 0.8 m/s when cruciform angle is 90°, close to 0.2 m/s at 67.5°, and close to 0.4 m/s at 0°. This power and efficiency map makes it possible for future engineers to tailor the design of their cruciform energy harvester to their specific power and efficiency needs

CLEAN WATER PRODUCTION PERFORMANCE MEASUREMENT INDICATORS AND FACTORS : A REVIEW ON ULTRAFILTER MEMBRANE

This review aims to answer the question relating to the problem of measuring the clean water production performance of the Ultrafilter membranes. This review has designed to study the research journal articles recently published (from 2000 to 2022) on the clean water production performance of ultrafilter membranes. The focus of this study was to unlock the influence of feed water quality, pre-treatment efficiency, Productivity, and energy consumption of the ultrafilter membrane on clean water production performance. The outcome of this review revealed that four indicators and thirteen potential factors have used for measuring the clean water production performance of ultrafilter membranes. The potential factors are the feed water pre-treatment, feed water pressure, chemically enhanced backwash, and osmotic pressure. Additionally, the pH, total suspended solids, turbidity, and chemical oxygen demand of feed water are the sources of cake layer formation that affect energy consumption and the operating cost of ultrafilter membranes in producing clean water. The findings of this review have a few industrial and policy implications. The outcomes of this review could be used by industrial engineers and consultants for designing the ultrafilter membrane system to optimize clean water production. The policy makers involved in technology selection for water filtration also can be used. The outcome of this study concludes that the ultrafilter membrane is an effective water treatment technology, but its performance depends on a few potential operating factors. This study recommends further research for optimizing the factors affect UFM performance in producing clean water

Investigation on Water Consumption Pattern in Traditional Malaysian Kampung: An Insight Study on Water and Environmental Issues

This research aims to investigate on water consumption pattern of traditional Malaysian kampung. Random sampling survey method was adapted to capture information on water consumption from the relevant stakeholders. The water consumption pattern is divided into five major categories such as cooking, drinking, washing, gardening and others. Study indicates that water consumption for a family of four persons is about 140 l/day, which is below average in Malaysian standard. Water consumption for cooking, drinking, washing, gardening and others found to be 7, 15, 8, 2.5, and 3 litres respectively. The findings benefit government agencies in developing strategy to supply clean water to the kampung people. The study suggests further in-depth study on the essentially important topics in order to generate robust information for developing a general model to be used for government policies