Numerical study of the effects of surface roughness on water disinfection UV reactor

Chemosphere ◽  
2016 ◽  
Vol 148 ◽  
pp. 108-117 ◽  
Author(s):  
Tipu Sultan ◽  
Sarfraz Ahmad ◽  
Jinsoo Cho
Keyword(s):  
Surface Roughness ◽  
Numerical Study ◽  
Water Disinfection ◽  
Uv Reactor

Methodology considering surface roughness in UV water disinfection reactors

2016 ◽  
Vol 70 (6) ◽  
Author(s):  
Tipu Sultan ◽  
Jin-Soo Cho
Keyword(s):  
Surface Roughness ◽  
Dose Distribution ◽  
Water Disinfection ◽  
Iterative Approximation ◽  
Roughness Effects ◽  
Ansys Fluent ◽  
Pipe Surface ◽  
Uv Reactor ◽  
Uv Lamp ◽  
Closed Conduit

AbstractWater disinfection making use of an ultraviolet (UV) reactor is an attractive procedure because it does not produce any by-products. In this work, the effects of pipe roughness on the performance of a closed-conduit water disinfection UV reactor were investigated. In order to incorporate the surface roughness effects, a simple, stable, highly accurate model, better than any iterative approximation, was adopted in the numerical simulations. The analysis was carried out on the basis of two performance indicators: reduction equivalent dose (RED) and system dose distribution. The analysis was performed using a commercial computational fluid dynamics (CFD) tool (ANSYS Fluent). The fluence rate within the UV reactor was calculated using UVCalc3D. The pipe surface roughness resulted in longer pathogen residence times and higher dose distribution among the pathogens. The effect of pipe surface roughness on RED depends on the Reynolds number and relative roughness. Pipe surface roughness plays an important role because UV reactors for water disinfection operate at moderate Reynolds numbers. In addition, the positioning of the UV lamp in the reactor plays an important role in determining the RED of the reactor. Search criteria for lamp-positioning are also proposed in the current work. The proposed CFD methodology can be used to analyse the performance of closed-conduit reactors for water disinfection by UV.

scholarly journals Numerical Study on Surface Roughness Measurement Based on Nonlinear Ultrasonics in Through-Transmission and Pulse-Echo Modes

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4855
Author(s):  
Maodan Yuan ◽  
Anbang Dai ◽  
Lin Liao ◽  
Yan Chen ◽  
Xuanrong Ji
Keyword(s):  
Surface Roughness ◽  
Numerical Study ◽  
Material Model ◽  
Nonlinearity Parameter ◽  
Fe Model ◽  
Roughness Measurement ◽  
Monitoring Method ◽  
Surface Roughness Measurement ◽  
Nonlinear Ultrasonics ◽  
Pulse Echo

Ultrasonic is one of the well-known methods for surface roughness measurement, but small roughness will only lead to a subtle variation of transmission or reflection. To explore sensitive techniques for surfaces with small roughness, nonlinear ultrasonic measurement in through-transmission and pulse-echo modes was proposed and studied based on an effective unit-cell finite element (FE) model. Higher harmonic generation in solids was realized by applying the Murnaghan hyperelastic material model. This FE model was verified by comparing the absolute value of the nonlinearity parameter with the analytical solution. Then, random surfaces with different roughness values ranging from 0 μm to 200 μm were repeatedly generated and studied in the two modes. The through-transmission mode is very suitable to measure the surfaces with roughness as small as 3% of the wavelength. The pulse-echo mode is sensitive and effective to measure the surface roughness ranging from 0.78% to 5.47% of the wavelength. This study offers a potential nondestructive testing and monitoring method for the interfaces or inner surfaces of the in-service structures.

Contact Residue for Simultaneous Removal of Vehicle’s Frequency and Surface Roughness in Scanning Bridge Frequencies Using Two Connected Vehicles

2021 ◽  
pp. 2171006
Author(s):  
Y. B. Yang ◽  
X. Q. Mo ◽  
K. Shi ◽  
Z. L. Wang ◽  
H. Xu ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Numerical Study ◽  
Contact Point ◽  
Connected Vehicles ◽  
Scanning Method ◽  
Contact Residue ◽  
Two Factors ◽  
Vehicle Response ◽  
Residual Response ◽  
Contact Response

Two factors are critical to the effectiveness of the vehicle scanning method for bridge frequencies. One is the frequency of the test vehicle itself. This can be eliminated by using the vehicle–bridge contact point response calculated from the vehicle response. The other is the surface roughness of the bridge, which can be removed by using the residual response of two connected vehicles. In this paper, it is demonstrated for the first time that both vehicle’s frequency and surface roughness can be simultaneously eliminated using the contact residue of two connected vehicles. Theoretically, a formulation is presented for both the contact response and residues. In the numerical study, the contact response is demonstrated to outperform the vehicle response as more bridge frequencies can be identified, while the contact residue is verified to work well for various surface roughnesses, vehicle spacings, and bridge damping ratios. For damped bridges with rough surfaces, the contact residue enables us to extract the first three bridge frequencies.

scholarly journals Effects of change in orientation and surface roughness of terrain oil thermally induced up slope flows in western Ghats: A numerical study

MAUSAM ◽  
2022 ◽  
Vol 46 (4) ◽  
pp. 367-376
Author(s):  
M. TIWARI ◽  
N. RAMANATHAN
Keyword(s):  
Numerical Simulation ◽  
Surface Roughness ◽  
Western Ghats ◽  
Roughness Length ◽  
Mesoscale Model ◽  
Numerical Study ◽  
Western Ghat ◽  
Thermally Induced ◽  
Slope Flow

ABSTRACT. The effect of change in orientation and surface roughness of terrain on the daytime up slope flow is investigated using a 2-dimensional mesoscale model. A realistic orography profile of western ghat is chosen for the purpose. Twelve hour of integrations are performed starting from sunrise. The numerical simulation have shown that the intensity of up slope flows remained practically unaffected by change of orientation of terrain. However, increase in roughness length decreases the intensity of developed flows. For comparison purposes, the results of previous investigators are verified with a change in slope angles.    

Effect of housing surface roughness on the performance of a centrifugal compressor for turbocharger: Experimental and numerical study

2021 ◽  
pp. 146808742110475
Author(s):  
Ealumalai Karunakaran ◽  
Sanket Mulye ◽  
Jawali Maharudrappa Mallikarjuna
Keyword(s):  
Surface Roughness ◽  
Numerical Analysis ◽  
Centrifugal Compressor ◽  
High Speed ◽  
Numerical Study ◽  
Experimental Results ◽  
Wall Turbulence ◽  
Low Flow ◽  
Pressure Losses ◽  
Compressor Performance

Centrifugal compressor plays a vital role in the performance of a turbocharger. The compressor contains an impeller and housing, including the vaneless diffuser and a volute. The high-speed flow from the impeller is diffused in the diffuser and volute, before being delivered to the engine. Hence, the housing flow characteristics affect the compressor performance and operating range. Generally, housing has noticeable surface roughness, especially in the volute. This study evaluates the effect of the volute surface roughness on the compressor performance by experimental and numerical analysis. The experiments are conducted for three different volute surface roughness levels to measure the overall compressor pressure ratio and efficiency. The uncertainty in the efficiency for experimental results is within ±0.5% pts. Also, steady-state numerical simulations are performed to analyse the flow mechanisms causing pressure losses. Then, a numerical analysis is done to understand the effect of roughness of the diffuser hub and shroud walls on the compressor performance. From the experimental results, it is found that the increase in the roughness level of the volute from the smooth surface by circa 900% and 1400% shows a significant reduction in the compressor efficiency at the design speed (N) and off-design speeds (0.87 and 1.13 N). The reductions of efficiency are about 0.5%–1% pts at the near surge point, 1%–1.5% pts at the peak efficiency point and 2%–2.5% pts at the near choke flow point. The CFD analyses show significantly higher near-wall turbulence and wall shear resulting in additional pressure losses. Also, it is found that the pressure losses are more sensitive to roughness of the diffuser shroud-wall than that of the hub-wall. On the other hand, the diffuser hub-wall roughness increases the radial momentum in the diffuser passage which suppress the flow separation at low flow rates.

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