Velocity Flow Field Characteristic on Nozzle Cavity using Central Composite Design of Computational Method for Dry Ice Blasting System

In the development of dry ice blasting nozzle geometry, the critical process parameters depend on particle jet velocity. However, very few researchers have attempted sensitivity on the velocity flow area of specific nozzle geometric parameters. A numerical simulation approach was performed in this paper using Ansys Fluent to investigate different nozzle parameters on the velocity flow field. A two-dimensional model is solved iteratively using averaged Navier-Stokes under Eulerian flow description. It was found that the velocity value increases that reach 550 m/s with an increment of the nozzle area ratio of up to 20 without influencing convergent angle and the velocity magnitude drop linearly from 525 m/s to 505 m/s in with the rise of divergent length that swell up to 700 mm and with constant convergent angle and convergent length.

Scour Hole Development in Natural Cohesive Bed Sediment around Cylinder-Shaped Piers Subjected to Varying Sequential Flow Events

Scour evolution and propagation around a cylinder in natural cohesive sediment was uniquely investigated under multi-flow event varying sequentially by velocity magnitudes. This flume study differs from others that only used test sediment with commercially available clays for single flow. The objective of this study was to explore the potential differences in scour hole development in natural riverbed sediments subjected to varying flow velocity scenarios, advancing our understanding from existing studies on scour. The study consisted of 18 experimental runs based on: velocity, flow duration, and soil bulk density. Scour hole development progressed initially along the cylinder sides, and maximum depths also occurred at these lateral locations. Scour hole depths were less for higher soil bulk densities (≥1.81 g/cm3) compared with lower densities, and erosion rates were slower. It was observed with all flow sequences that scour depths were similar at the end of each experimental run. However, scour initiation was observed to be time dependent for soils with higher bulk density (1.81–2.04 g/cm3) regardless of flow velocity sequences. The observed time dependency suggests a process feedback with the scour hole development initiated at the cylinder sides, which influence local 3D hydraulics as the scour hole depth progresses.

Reduction of Lead and Antimony Ions from the Crystal Glass Wastewaters Utilising Adsorption

The presented research examined five adsorbents, i.e., zeolite 4A, a mixture of three zeolites (4A, 13X, and ZSM-5), natural zeolite (tuff), activated carbon, and peat, and their potential capability for removal of exceeded ions of lead (Pb), antimony (Sb), sulphates (SO42−), and fluorides (F−) from real wastewater generated in the crystal glass industry, which was previously treated in-situ by flocculation, with the aim to attain the statutory values for discharge into watercourses or possible recycling. The screening experiment evidenced that the tuff was the most suitable adsorbent for the reduction of Pb (93.8%) and F− (98.1%). It also lowered wastewater’s pH sufficiently from 9.6 to 7.8, although it was less appropriate for the reduction of Sb (66.7%) as compared to activated carbon (96.7%) or peat (99.9%). By adjusting the pH of the initial wastewater to pH 5, its adsorption capacity even enlarged. Results from the tuff-filled column experiment revealed reduction of Pb up to 97%, Sb up to 80%, and F− up to 96%, depending on the velocity flow, and thus it could be used for post-treatment (and recycling) of wastewaters from the crystal glass industry. Moreover, the system showed an explicit buffering capacity, but negligible reduction of the SO42−.

EFFECT OF THREE-WHEELED VEHICLES ON THE CAPACITY OF A TRAFFIC STREAM

Due to the tremendous development of the number and types of vehicles and a large number of traffic congestions, the phenomenon of the spread of three-wheeled vehicles, which is characterized by ease of movement, has recently appeared in Iraq because of a small space it occupies for its movement. The increase in their numbers exceeds the number of heavy vehicles in most urban areas in Iraq. Therefore, the current study has been devoted to studying the effect of those vehicles with three tires using a simulation program that has been previously developed and has been calibrated to suit the normal sections where the characteristics of these vehicles were included in terms of speed and length. Different ratios were used, ranging from (0-15) % for the first lane only. Some general traffic characteristics were examined, such as velocity-flow and flow-density and density-velocity relationship. The results showed that the presence of this type of vehicle has a significant impact on reducing road efficiency and increasing traffic congestion. The study recommends that a particular lane with a width of 2m on both directions of the roads be designated for the movement of these vehicles and keep them away from interference in the traffic flow of other cars.

Global Mapping of Mouse CSF Flow via HEAP-METRIC Phase-contrast MRI

Roles of Cerebrospinal fluid (CSF) in brain waste clearance and homeostasis has been increasingly recognized, thus measuring its flow dynamics could provide important information about its function and perturbance. While phase-contrast MRI can be used for non-invasive flow mapping, so far its mapping of low velocity flow (such as mouse brain CSF) is not possible. Here we developed a novel generalized Hadamard encoding based multi-band acceleration scheme dubbed HEAP-METRIC (Hadamard Encoding APproach of Multi-band Excitation for short TR Imaging aCcelerating), and with significantly increased SNR per time, HEAP-METRIC phase-contrast MRI achieved fast and accurate mapping of slow (~102 micron/s) flow. Utilizing this novel method, we revealed a heterogeneous global pattern of CSF flow in the awake mouse brain with a averaged flow of ~200 micron/s, and further found isoflurane anesthesia reduced CSF flow that was accompanied by reduction of glymphatic function. Therefore, we developed the novel HEAP-METRIC phase-contrast MRI for mapping low velocity flow, and demonstrated its capability for global mapping of mouse CSF flow and its potential alterations related to various physiological or pathological conditions.

Analisis Kavitasi pada Saluran Transisi dan Peluncur Pelimpah Bendungan Kluet – Model Fisik Skala 1:60

River Region of Baru-Kluet has a steep slope contour and high rainfall so that it is vulnerable to flooding while during the dry season rice fields experience drought due to lack of water. Therefore, a dam is built to mitigate these issues. The spillway is a flow-control component in the dam which is used to improve regulation and enlarge the flow rate that will cross the spillway building. Spillway that has a steep slope is vulnerable to hydraulic behavior called cavitation. The experiment was carried out at the River and Coast Laboratory of Syiah Kuala University, Indonesia. This study aims to determine the value of the damage cavitation index interval in each series and discharge variation. Cavitation index analysis method used formula of ratio between local water pressure and flow velocity. Flow velocity and pressure at each outflow discharge was collected from the experiment. The results of the damage cavitation index interval in the 0 series and the modified series are located at level 1 for the transition region, level 3 for the launcher region and level 2 for the launcher region of modified series. It is found that the change in series 0 to a modified series with extending width in the side channel, lowering the elevation of side channel, and displacement sill in the transition channel with the aim of reducing the flow velocity. This change still has the possibility of cavitation damage, but it is much safer than the cavitation results of the 0 series. High quality of materials or concrete are not recommended because they are expensive and economically unfeasible, therefore the use of slot aeration/aerator is a suitable option for this case. Keyword: Dam, spillway, cavitation, model test.

Cerebrovascular super-resolution 4D Flow MRI – using deep learning to non-invasively quantify velocity, flow, and relative pressure

ABSTRACTThe development of cerebrovascular disease is tightly coupled to changes in cerebrovascular hemodynamics, with altered flow and relative pressure indicative of the onset, development, and acute manifestation of pathology. Image-based monitoring of cerebrovascular hemodynamics is, however, complicated by the narrow and tortuous vasculature, where accurate output directly depends on sufficient spatial resolution. To address this, we present a method combining dedicated deep learning and state-of-the-art 4D Flow MRI to generate super-resolution full-field images with coupled quantification of relative pressure using a physics-driven image processing approach. The method is trained and validated in a patient-specific in-silico cohort, showing good accuracy in estimating velocity (relative error: 12.0 ± 0.1%, mean absolute error (MAE): 0.07 ± 0.06 m/s at peak velocity), flow (relative error: 6.6 ± 4.7%, root mean square error (RMSE): 0.5 ± 0.1 mL/s at peak flow), and with maintained recovery of relative pressure through the circle of Willis (relative error: 11.0 ± 7.3%, RMSE: 0.3 ± 0.2 mmHg). Furthermore, the method is applied to an in-vivo volunteer cohort, effectively generating data at <0.5mm resolution and showing potential in reducing low-resolution bias in relative pressure estimation. Our approach presents a promising method to non-invasively quantify cerebrovascular hemodynamics, applicable to dedicated clinical cohorts in the future.

Mathematical modeling of non-Newtonian fluid in arterial blood flow through various stenoses

Since the stenosis geometry of some cardiovascular patients cannot be described by a vertically symmetric function throughout the stenosis, so it motivates us to study the blood flow through a vertically asymmetric stenosis. In addition, we compare the flow quantities in bothvertically symmetric and asymmetric stenoses. The vertically symmetric stenosis is explained by a vertically symmetric function such as an exponential function in bell shape and a cosine function in cosine shape. The vertically asymmetric stenosis is interpreted by a vertically asymmetric function such as the combination of two different stenosis shapes. Blood is treated as a non-Newtonian fluid which is represented in the power-law model. The finite difference scheme is used to solve governing equations for obtaining the flow quantities such as axial velocity, radial velocity, flow rate, resistance to flow, and skin friction. We investigated the way that the stenosis height, stenosis length, and non-Newtonian behavior affect the flow quantities through three various stenoses. The flow quantities in the bell shape and cosine shape of stenosis show significantly different behavior. Moreover, we found that the flow quantities in the single shape (bell shape or cosine shape) have the same behavior as the flow quantities in the combined shape in the first half part, but have a slightly different behavior in the last half part.