Effect Of Surface Roughness Research Articles

Effect of surface roughness on the efficacy of Plasma Activated Mist (PAM) for inactivation of Listeria innocua and Klebsiella michiganensis.

Cold plasma generated by dielectric barrier discharge (DBD) and DBD combined with nebulized liquid microdroplets to generate plasma-activated mist (PAM) have shown the potential as a surface decontamination method for the food industry. The objective of this research was to measure the microbial inactivation caused by DBD and by PAM on tryptic soy agar (TSA) and on glass slides and to determine the efficacy of PAM on selected surfaces having different surface topographies. Tryptic soy agar in Petri dishes and on glass slides (surface roughness Pq=0.28±0.02μm) was inoculated with either 0.1mL of inoculum containing Listeria innocua (8.4±0.1 log CFU/mL) or Klebsiella michiganensis (8.8±0.2 log CFU/mL) and exposed to either DBD or PAM for 5 to 20min. Glass slides, grape tomatoes (Pq=5.17μm±0.53μm), limes (Pq=18.76μm±3.00μm), and spiny gourds (Pq=101.50μm±10.95μm) were also surface-inoculated with L. innocua or K. michiganensis and exposed to PAM for 5 to 20min. No significant difference in microbial inactivation was observed between DBD plasma and PAM for all treatment times. The smoothest surface (glass) showed the highest reduction in L. innocua (3.4±0.2 log CFU/item) and K. michiganensis (5.7±0.0 log CFU/item) after PAM treatment. The roughest surface (spiny gourd) yielded a significantly lower reduction for L. innocua (1.0±0.2 log CFU/item) and K. michiganensis (1.8±0.1 log CFU/item). L. innocua was less susceptible to inactivation by PAM compared K. michiganensis. This study highlighted the importance of surface roughness on microbial inactivation of L. innocua and K. michiganensis by DBD and PAM on produce surfaces.

Experimental Investigation of Heat Transfer to Supercritical Pressure Fluid in Tubes with Rough Inner Surface

Abstract The highly corrosive environment inside a Supercritical Water-Cooled Reactor places stringent demands on the fuel rod cladding material, particularly requiring it to have strong corrosion resistance. However, within a refueling cycle, an oxide layer is growing on the surface of the fuel rods. In any case, the heat transfer to water under supercritical pressure conditions is an overly complex phenomenon, since the thermophysical properties of the fluid show drastic variations with respect to the temperature around the pseudo-critical temperature. An increase in the surface roughness height has an impact on heat transfer. To provide insight into the effect of surface roughness on heat transfer an experimental database, using the surrogate fluid R134a, covering a range of flow conditions is established. The database consists of reference data, obtained in a conventional hydraulic tube and of data obtained in a tube with an artificially roughened inner surface. In the present work, the impact of the surface roughness on heat transfer is evaluated, comparing the results obtained in the smooth tube, to the results obtained in the tube with rough inner surface. Heat transfer is enhanced when the Reynolds number is large enough and heat transfer deterioration can be suppressed or shifted to larger bulk enthalpy, due to the roughness. Furthermore, existing empirical correlations are assessed against the newly generated experimental database. It is concluded that none of the available correlations satisfactory predicts the experimental data over the entire range of Reynolds numbers, surface roughness and wall-to-bulk temperature ratios.

The Influence of Initial Surface Roughness on the Current-Carrying Friction Process of Elastic Pairs.

To investigate the effect of the initial surface roughness on the performance at the initial stage of the current-carrying friction of an elastic friction pair, experiments were conducted using a self-made current-carrying friction and wear tester. The results indicate that under the experimental conditions, the lifespan of the friction pair decreases as the surface roughness and load decrease. When the surface roughness is Ra 0.2 μm and the load is 0.025 N, the lifespan is the longest, reaching 320 cycles, with an average contact resistance of 0.045 Ω and a standard deviation of 0.009 Ω. During the normal service period of the friction pair, the main wear mechanism is furrowing. As adhesion and tearing occur, the electrical contact performance begins to degrade. The impact of arc erosion on the wear surface is far greater than that of mechanical wear. This provides a reference for the design and manufacture of current-carrying friction pairs represented by connectors.

Modeling and simulation of the effect of surface roughness on the Fowler-Nordheim conduction in MOS structures

Abstract A compact Fowler-Nordheim (FN) tunneling current model is derived to describe the non-ideal, surface roughness-related relationship between current and voltage in a metal-oxide-semiconductor (MOS). This relationship is achieved by applying a fractal continuum Laplacian operator in the 1D Schrödinger equation, resulting in a model that extends the standard FN to account for surface inhomogeneities through a fractional power α. Our error analysis predicts significant inaccuracies in the extracted FN parameters when using the standard FN model to interpret rough surface data.
A methodology for extracting FN fractal parameters and the flat band voltage via a fractal FN plot is proposed. Simulated datasets and real measurements of Al/SiO₂/4H-SiC capacitors are used to validate the model. Comparison of the parameters extracted using the fractal FN model and the standard FN model confirms the predictions from the error analysis and the suitability of the fractal FN model. The fractal FN model offers a potential explanation for the large discrepancies observed in FN parameters reported in the literature.

Effect of surface roughness on the fretting corrosion behavior of Inconel 690 alloy tube

Abstract Surface roughness which is an important index to evaluate a material’s surface properties, can strongly influence the service performance of steam generator tubes in nuclear power plants. This study used experimental tests and finite element analysis to investigate the fretting corrosion mechanisms of Inconel 690 alloy tubes of three roughness surfaces (Sa “Surface Roughness Average” ≈ 0.09, 0.25, and 0.50 μm) under 25 ℃ and 100 ℃ artificial sea water (3.5% NaCl solution) conditions. Results showed that surface roughness affected the fretting damage and electrochemical corrosion behavior of the alloy tubes significantly. This is mainly due to surface roughness also belongs to a kind of micro-defects, which would influence the fretting contact state and corrosive medium effect, and temperature influenced oxidation. All these conditions led to different fretting corrosion damage.

Obtaining Damage Parameters for Out‐of‐Plane Adhesive Failure in Epoxy–Aluminum Interface

ABSTRACTThis study investigates the out‐of‐plane adhesive failure mechanisms at the interface between Araldite 2011 epoxy adhesive and aluminum surfaces. Pull‐off tests were performed on aluminum substrates, which were prepared using various grades of sandpaper to evaluate the effect of surface roughness on the adhesive strength. The results showed that aluminum surfaces treated with P150 sandpaper provided better adhesion compared to other surface preparations. However, scanning electron microscopy (SEM) analysis and visual inspections of the fracture surfaces confirmed that interfacial adhesive failure was the dominant failure mode. A modified triangular traction–separation (TS) damage model was developed to characterize the adhesive/aluminum interface, taking into account the influence of surface roughness. This model was constructed using load–displacement data from the pull‐off tests. Additionally, a 2D axisymmetric finite‐element model was created to simulate the mechanical behavior of the system, and the TS model was validated against experimental results. The numerical analysis revealed that the interfacial region experiencing adhesive failure played a critical role in the load–displacement response of the pull‐off specimens.

A new forcing approach for wall-modeled simulation of rough-wall turbulent flows

The effect of rough surface on turbulent flows is usually investigated using direct numerical simulation (DNS) with either body-fitted grids or immersed boundary method. Both methods, however, require a significant number of grids to resolve all rough scales, resulting in intolerable computational cost. In this paper, a new volume forcing approach is developed to simulate wall-bounded turbulent flows with surface roughness at the same computational cost as that with smooth walls. Specifically, two extra forcing terms are introduced in the Navier–Stokes equations to mimic roughness effects. One is the feedback force operating within the roughness cell and ensuring zero velocity at the grid points located therein. The other represents the vortex force around the roughness surface. A direct comparison with the model proposed in literature shows a significant improvement in the prediction of mean flow and Reynolds stresses. To further validate the new forcing model, simulation of channel flow with cubical roughnesses is implemented, which shows a good agreement with fully resolved DNS.

Analysis of the effect of rough contact surfaces on the electrical properties of composite skin

Analysis of the effect of rough contact surfaces on the electrical properties of composite skin

Distributed Sand-Grain Roughness Effects on Blunt-Body Hypersonic Transition and Heating

An experimental investigation of distributed sand-grain surface roughness effects on boundary-layer transition and convective heating has been performed. Two representative entry vehicle geometries, a spherical-cap aeroshell and a sphere-cone aeroshell, were considered. Multiple cast ceramic wind tunnel models of each geometry were fabricated with various roughness heights to simulate an ablated thermal protection system. Wind tunnel testing was performed at Mach 6 over a range of Reynolds numbers sufficient to produce laminar, transitional, and turbulent flow. Aeroheating and boundary-layer transition onset data were obtained using global phosphor thermography. The experimental heating data are presented herein, as are comparisons to laminar and turbulent smooth-wall heat transfer distributions from computational flowfield simulations.

Investigation of surface roughness induced attenuation of reflected waves using a quasi-Monte Carlo method

Abstract An understanding of the influence of surface roughness on wave scattering and accurate predictions of wave amplitudes are crucial for quantitative ultrasonic nondestructive testing and evaluation. In this work, the effects of surface roughness on the reflection coefficient are investigated using a quasi-Monte Carlo (QMC) method. The wave fields reflected from smooth and rough interfaces with an immersion transducer are modeled using the Rayleigh integral method, and the solutions are efficiently calculated using the QMC method for interfaces constructed using pseudo-random samples. The reflected wave fields are simulated and presented, and the properties of coherent and incoherent waves affected by interface roughness are discussed. The surface roughness induced attenuation of reflected waves is calculated using the ratio of received pressures for waves reflected from rough and smooth interfaces, and the predicted results are compared with those obtained using other recognized methods. It is shown that at low levels of roughness, excellent agreement is obtained between the results from the QMC method and the well-known Kirchhoff approximation, while for high levels of roughness, where the Kirchhoff theory gives pessimistic results, the predicted values agree well with those simulated using a finite element modeling approach, thus verifying the effectiveness of the proposed method.

A MINI REVIEW ON THE EFFECTS OF SURFACE ROUGHNESS IN MICROFIUIDICS CHANNELS

The effects of surface roughness at low Reynolds numbers are more pronounced and critical in microchannels due to the relative size of roughness to channel dimensions. Surface roughness in microfluidic channels originates from the machining process during fabrication. This review examines how surface roughness, resulting from various manufacturing processes, influences the performance of microfluidic devices. Different patterns of surface roughness generated through techniques such as photolithography, etching, precision machining, and 3D printing are highlighted. These techniques yield distinct surface characteristics that affect critical microchannel properties, including fluid flow, pressure drop, and stress distribution. In addition to that, specific fabrication methods can minimize surface roughness, enhancing the performance of microchannels for applications in diagnostics, lab-on-a-chip systems, and small-scale heat exchangers are addressed. The review provides insights into selecting optimal fabrication techniques to achieve desired performance characteristics in microfluidic devices.

Morphological Features Influence the Drug Loading and Delivery Efficacy of Photoactivatable Gold Nanocarriers for Antitumor Photo/Chemotherapy.

Photoactivatable gold nanocarriers are transforming antitumor therapies by leveraging their distinctive physicochemical properties, enabling targeted drug delivery and enhanced therapeutic efficacy in cancer treatment. This study systematically investigates how surface topography and morphology of gold nanocarriers influence drug loading capacity, light-to-heat conversion efficiency, and overall therapeutic performance in photo/chemotherapy. We synthesized four distinct morphologies of gold nanoparticles: porous gold nanocups (PAuNCs), porous gold nanospheres (PAuNSs), solid gold nanocups (SAuNCs), and solid gold nanospheres (SAuNSs). By examining these morphologies, we isolated the effects of surface roughness, porosity, and inner cavity structures on the critical therapeutic parameters. Our findings reveal that PAuNCs exhibit superior drug loading capabilities due to their enhanced surface area and porosity, facilitating greater interaction with therapeutic agents. Whereas, dissolution kinetic modeling confirmed that porosity contributes to improve diffusion-controlled drug release. In vitro studies on HepG2 cancer cells demonstrated that PAuNCs markedly improved cellular uptake, resulting in a dramatic reduction in cell viability to 3% and a notable increase in apoptosis (60.45%). Under near-infrared (NIR) irradiation, PAuNCs effectively induced localized hyperthermia (46.7 °C) and significantly inhibited tumor growth in an in vivo HepG2 tumor mice model compared with alternative nanogold morphologies. This research underscores the critical role of surface roughness, porosity, morphology, and cavitation in optimizing drug delivery and enhancing therapeutic outcomes of photoactivatable gold nanocarriers for collaborative photochemotherapy.

Detailed Analysis of Friction in Water-Lubricated Bearings Under Boundary Lubrication: Model Development and Experimental Validation

Abstract A novel friction model for water-lubricated bearings under boundary lubrication conditions is proposed. The effects of speed, load, surface roughness, and material properties on the friction coefficient are examined. The model is validated through experimental tests using NBR and UHMWPE materials, demonstrating reliability and applicability. The impact of varying speed and load on lubrication states is analyzed, with a focus on the behavior of microconvex contact friction under boundary lubrication conditions. Based on the verified friction model, the influence of surface roughness and texture direction on bearing performance is also explored, offering actionable insights for optimizing bearing design. This model provides critical insights for enhancing friction management and noise reduction in water-lubricated bearings, offering valuable guidance for their design and manufacturing.

Theoretical modeling of the interfacial shear and contact stresses of 2D braided composite cylinders

AbstractThis research aims to develop an analytical model to predict the interfacial shear stress distribution and contact stress of 2D braided composite cylinders. For this purpose, a tubular structure including a helix braid on a cylindrical mandrel is considered. The interfacial shear stress and axial tensile stress in the composite structure was estimated by applying shear lag assumptions. The contact normal stress and adhesion energy were estimated by applying the assumptions of Johnson‐Kendall‐Robert (JKR) and the Hertzian contact stress theory. The results show that the geometry of the braid and different braid yarn paths have a significant influence on the interfacial shear stress, normal stress in the contact zone, and adhesion energy of composite cylinders. As a novel approach, the proposed model considers the effect of surface roughness in the composite. The results of a parametric study indicated that the composite cylinders with larger braiding angles have lower debonding initiation force. The results also showed that the yarn diameter affected the pullout force in composite cylinders by a large extent.Highlights Normal contact stress and adhesion energy of composite cylinders are affected by the braid yarn path. The 30° composite presented the largest adhesion energy and normal contact stress. Normal tensile stress and interfacial shear stress are influenced by the reinforcement path in the composite. Normal tensile stress and interfacial shear stress in composite cylinders decreased with increased braid angle.

Addendum to ‘Assessment of offshore wind power including effects of sea surface roughness using observed wind statistics’: Assessment using sea surface roughness depending on spectral bandwidth of ocean waves

This addendum addresses the assessment of offshore wind power based on observed mean wind speed statistics from 11 sites in the North Sea and the North Atlantic. The wind gust and the ambient turbulence level are also estimated by adopting a wind gust spectrum. The sea surface roughness is specified using a recently published sea surface drag coefficient given in terms of the spectral bandwidth of ocean waves. The results are supplementary to those in a recent paper published by the present authors using the same mean wind speed statistics and wind gust spectrum, but with a different sea surface roughness formula depending on significant wave height and spectral wave steepness. It is demonstrated how the spectral bandwidth affects the assessment of the offshore wind power and the ambient turbulence level. Thus, since the spectral bandwidth is a frequently used parameter to characterize wave conditions the results should be useful.

Effects of surface roughness of a waveplate on the development of diffractive polarization speckle

A rough-surfaced retardation plate is a particular polarization-dependent phase modulation device, whose performance is affected by its surface roughness structures. In previous research [J. Opt. Soc. Am. A 32, 2346 (2015)JOAOD60740-323210.1364/JOSAA.32.002346], its decorrelation and depolarization effects have been investigated under an assumption of a rough surface model with large covariance of thickness fluctuations, giving a fully developed speckle field by transmission/reflection. This paper continues the analysis of the rough-surfaced retardation plate and then focuses on a smooth roughness model. When the thickness fluctuation is relatively small, partially developed speckle will be generated. The statistics of partially developed polarization speckle with non-uniform spatial distribution of polarization state will be discussed in the form of the matrix elements of the coherence–polarization matrix. The propagation of the partially developed speckle field will be traced within the framework of the complex-valued ABCD matrix theory under paraxial approximation to reveal the evolution of its degree change of coherence and polarization on propagation. This means that Gaussian apertures are included in the optical train of elements. The differences in statistical features from fully developed polarization speckle are emphasized.

Peristaltic pumping of viscoelastic fluid in a diverging channel: effects of magnetic field and surface roughness

Purpose Surface properties (smooth or roughness) play a critical role in controlling the wettability, surface area and other physical and chemical properties like fluid flow behaviour over the rough and smooth surfaces. It is reported that rough surfaces are offering more significant insights as compared to smooth surfaces. The purpose of this study is to examine the effects of surface roughness in the diverging channel on physiological fluid flows. Design/methodology/approach A mathematical formulation based on the conservation of mass and momentum equations is developed to derive exact solutions for the physical quantities under the assumption of low Reynolds numbers and long wavelengths, which are appropriate for biological transport scenarios. Findings The results reveal that an increase in surface roughness reduces axial velocity and volumetric flow rate while increasing pressure distribution and turbulence in skin friction. Research limitations/implications These findings offer valuable insights for biological flow analysis, highlighting the effects of surface roughness, non-uniformity of the channel and magnetic fields. Practical implications These findings are very much applicable for designing the pumping devices for transportation of the fluids in non-uniform channels. Originality/value This study examines the impact of surface roughness on the peristaltic pumping of viscoelastic (Jeffrey) fluids in diverging channels with transverse magnetic fields.

New Insight into the Effect of Particle Surface Roughness on Flotation Efficiency: An Experimental and Theoretical Analysis

New Insight into the Effect of Particle Surface Roughness on Flotation Efficiency: An Experimental and Theoretical Analysis

TiO2 nanotubes incorporated into a glaze-coating ceramic: surface roughness, color, and antibiofilm activity.

This study evaluated the surface roughness, color change, and antibacterial effect of a ceramic glaze enhanced with TiO2 nanotubes (n-TiO2). n-TiO2 (0, 2, 2.5, and 5 wt%) was added to a ceramic glaze powder, applied to the surface of forty feldspathic ceramic specimens, and sintered. The surface roughness average (Ra) before glaze application (T0) and after glaze crystallization (T1) was measured using a profilometer. The colorimetric alteration was determined by CIEDE2000 (ΔE00) and CIELab (ΔEab), and the whiteness index for dentistry (ΔWID). The antibacterial effect against S. mutans and S. sanguinis was evaluated (CFU/mL). Data were analyzed by two-way repeated-measures ANOVA, followed by the Bonferroni test (α = 0.05). No differences in ΔEab and ΔE00 were observed among groups (p > 0.05), and ΔWID was only affected by 5% n-TiO2. All groups surpassed the perception thresholds of 1.8 (ΔE00) and 2.3 (ΔEab). At T0, no Ra differences were detected among groups (p > 0.05). In T1, Ra decreased (p < 005) compared to T0, but 5% n-TiO2 increased roughness compared to the control group (without n-TiO2). The incorporation of n-TiO2 into the glaze powder did not impair bacteria adhesion, and no differences in biofilm formation were found among the concentrations (p < 0.05). The ceramic covered with a glaze containing 5% n-TiO2 caused minimal interference in the color and roughness with no effect on biofilm formation.

Effect of surface roughness on the microbiologically influenced corrosion (MIC) of copper 101

Effect of surface roughness on the microbiologically influenced corrosion (MIC) of copper 101