Effect Of Surface Roughness Research Articles

Combined Effects of Surface Roughness, Solubility Parameters, and Hydrophilicity on Biofouling of Reverse Osmosis Membranes

The fouling of protein on the surface of reverse osmosis (RO) membranes is a surface phenomenon strongly dependent on the physical and chemical characteristics of both the membrane surface and the foulant molecule. Much of the focus on fouling mitigation is on the synthesis of more hydrophilic membrane materials. However, hydrophilicity is only one of several factors affecting foulant attachment. A more systematic and rationalized methodology is needed to screen the membrane materials for the synthesis of fouling-resistant materials, which will ensure the prevention of the accumulation of foulants on the membrane surfaces, avoiding the trial and error methodology used in most membrane synthesis in the literature. If a clear correlation is found between various membrane surface properties, in combination or singly, and the amount of fouling, this will facilitate the establishment of a systematic strategy of screening materials and enhance the selection of membrane materials and therefore will reflect on the efficiency of the membrane process. In this work, eight commercial reverse osmosis membranes were tested for bovine serum albumin (BSA) protein fouling. The work here focused on three surface membrane properties: the surface roughness, the water contact angle (hydrophilicity), and finally the Hansen solubility parameter (HSP) distance between the foulant understudy (BSA protein) and the membrane surface. The HSP distance was investigated as it represented the affinities of materials to each other, and therefore, it was believed to have an important contribution to the tendency of foulant to stick to the surface of the membrane. The results showed that the surface roughness and the HSP distance contributed to membrane fouling more than the hydrophilicity. We recommend taking into account the HSP distance between the membrane material and foulants when selecting membrane materials.

The Effect of Ellipsoidal Particle Surface Roughness on Drag and Heat Transfer Coefficients Using Particle-Resolved Direct Numerical Simulation

The purpose of this study is to estimate the effect of roughness layer thickness on the heat transfer and drag coefficients of ellipsoidal particles. Using an OpenFOAM-based particle-resolved direct numerical simulation (PR-DNS) method, we calculated the drag coefficient and Nusselt number for an isolated axisymmetric nonspherical particle with a rough surface in a uniform flow. The PR-DNS results indicate that the drag coefficient varies linearly with the effective roughness Sef at different angles, which can be expressed as CD=kSef−1+CD0. The changes in k are consistent with the Happel and Brenner equation. Furthermore, the influence of roughness on the heat transfer efficiency factor can be represented by Ef=Sef−65. The models for the drag coefficient and Nusselt number are valid within the ranges 1.25≤Ar≤2.5,1≤Sef≤2, and 10≤Rep≤200, thereby extending the applicability of the equations developed for smooth particles. These newly developed correlations for the drag coefficient and Nusselt number can be utilized for non-isothermal flows of particle mixtures containing materials with various rough-surfaced ellipsoids.

Heat transfer analysis of hybrid nanofluid under the effects of surface roughness along with velocity and thermal slips

AbstractSurface roughness has a great impact on the peristaltic motion of nanofluid flow and plays an important role in engineering, manufacturing, and material sciences. During tissue engineering, imaging techniques, implant surface finish, surgical instrument texture, and tissue engineering, and so forth. This study explores the effects of electrical double layers, surface roughness, velocity slip, and thermal slip to investigate the heat transfer rate of cobalt and alumina nanoparticles with water through uniform and nonuniform horizontal tubes. In the present study, the Jeffrey nanofluid flow model is chosen to investigate the heat transfer phenomenon of hybrid nanofluids based on alumina and cobalt nanoparticles suspension in water. The effects of electroosmosis, surface roughness, viscous dissipation, heat source/sink parameter, velocity, and thermal slips are also under consideration during the peristaltic motion of hybrid nanofluid in uniform and nonuniform tubes. The mathematical software MATHEMATICA 13.3 is utilized to find the exact solution and graphical results to investigate the complicated flow behavior. It is noticed that the velocity near the walls of the tube is lower for the surface roughness parameter and higher in the core part. The behavior of velocity for the remaining parameter is the opposite. The temperature of the current fluid flow increases for all parameters except the surface roughness parameter. The effects of velocity for hybrid nanofluid are prominent as compared with nanofluid in the core part. The temperature profile and heat transfer rate for hybrid nanofluids are lower as compared with nanofluids, which shows the cooling effects. This study is beneficial for hyperthermia, gene therapy, drug delivery, and tissue engineering.

Pore-scale study of droplet settling on a heterogenous surface structure

Equilibrium contact angle of a droplet is influenced by surface characteristics and fluid properties. In addition to increasing the solid–liquid contact line, surface roughness also alters the surface free energy, which has a significant influence on contact angle values. Droplets are more likely to impinge on vertices as surface roughness increases. Anisotropic wetting of chemically heterogeneous surfaces further controls the total surface free energy. The free energy Lattice Boltzmann method is utilized to study the effects of wettability heterogeneity and roughened surfaces. Initial model comparisons with experiments showed excellent agreement. The rough surface is modeled with different pillar shapes on a smooth wall, with surface wettability ranging from hydrophilic to neutral conditions. The length scale of surface patterns matches the droplet size, making the Cassie–Baxter and Wenzel equations inapplicable. Results indicate that droplets pin on the vertices of rectangular pillars, while frustum shapes facilitate movement. Studies cover nearly neutral wet, moderately wet, and strongly wet conditions. The effects of relative surface roughness, roughness distribution, mixed wetting surfaces, and body force on equilibrium contact angle are examined. Additionally, the interaction between fluid flow and surface roughness elements shows that smaller spacing and greater height of roughness elements enhance thermal performance, with Nusselt numbers fluctuating significantly. Findings suggest that the ratio of droplet size to pillar surface area is crucial for minimizing surface free energy. On superhydrophilic surfaces, droplet pinning at pillar edges causes the surface to behave hydrophobically. In mixed-wet rough surfaces, pillar wettability significantly influences the equilibrium contact angle.

The Effect of Channel Surface Roughness on Two–Phase Flow Patterns: A Review

This review article highlights the critical impact of surface roughness in modifying the structure of two-phase flow within mini- and microchannels, particularly in processes such as boiling and condensation. Channel surface roughness enhances flow resistance, affects the distribution of vapor bubbles, and enhances heat transfer by providing additional nucleation sites. Several experiments have shown that while increased surface roughness enhances the efficiency of heat transfer, increased flow resistance may hurt system performance. This is so because too high a surface roughness negatively impacts flow resistance, a factor of importance in the optimization for a balance between heat transfer and flow resistance, especially in high-performance compact heat exchangers. Furthermore, the review identifies that higher-degree measurement and characterization techniques of the surface roughness are increasingly required, as traditional 2D parameters may not fully represent the actual physics of complex surface interactions in two-phase flow systems. Consequently, the article calls for further research that can examine the exact relationship between roughness, flow structure, and thermal performance with the aim of improving design strategies for future heat exchanger technologies.

Effects of Surface Roughness Obtained by Milling on Interface Bonding Quality for 316H during Metal Additive Forging

The metallurgical bonding quality of bonded joints is affected by the substrate surface condition in metal additive forging process, and the surface roughness serves as a critical indicator for the surface condition. Nevertheless, the effect of surface roughness obtained by milling on interface bonding quality(IBQ) remains unclear, resulting in the lack of effective evaluation criteria for surface roughness in the milling process. This study prepared samples with various surface roughness through milling, and introduced three parameters, Ra, Rc, and Rsm, to quantify surface roughness. The interfacial morphology, elemental distribution, and mechanical properties were used to characterize the IBQ, and the influence of surface roughness on the IBQ was finally revealed. The results show that a reduction in surface roughness obtained by milling leads to an improvement in interfacial bonding, more uniform elemental distribution, and enhanced mechanical properties, all of which were related to the size of the initial voids and the dynamic recrystallization mechanism of the bonding interface. And the interface bonding process with various surface roughness involves grain boundary bulging and continuous dynamic recrystallization mechanisms. Finally, the Ra 1.2 μm was recommended as the evaluation criteria in milling process, and a high-feed face milling cutter equipped with wiper edge was suggested for machining to achieve high-quality and high-efficiency cutting of the substrate. This study provide a theoretical basis and practical guidance for the efficient acquisition of substrate surfaces suitable for interface bonding in metal additive forging process.

Surface condition driven fatigue performance of laser powder bed fusion H13 steel

Surface variation is an inherent imperfection in the laser powder bed fusion (LPBF) processed samples, comprising of primary roughness (PRR) from the melt pool solidification and secondary roughness (SER) from adhered powder particles. Components under cyclic loading are sensitive to surface defects, making surface finishing crucial for fatigue-bearing parts. However, this undermines LPBF’s advantage of creating high-performance and geometrically complex components. This study examines the effect of surface roughness on fatigue crack initiation in LPBF H13 steel, a high-strength alloy with a tensile strength of 1800 MPa. The focus is on scenarios where contour scanning strategies are not employed. Vertically deposited samples were subjected to three surface conditions: as-built (AB) with PRR + SER, half-polished (HP) with only PRR, and well-machined (M) with no PRR or SER. Optical and digital surface roughness characterization and stress-controlled fatigue testing were performed. Results revealed that while AB-samples showed significantly rough surface compared to HP-samples, their fatigue performance did not reduce. In contrast, M-samples had a slight improvement in roughness but exhibited a fatigue life increase by a factor greater than 17. This was attributed to the PRR, specifically the solidification valleys between the neighboring melt pools. Factographic analysis showed that the PRR-driven fatigue crack initiation is a critical determinant of fatigue performance.

Effects of surface roughness on the drag coefficient of finite-span cylinders freely rolling on an inclined plane

We present an experimental investigation aimed at understanding the effects of surface roughness on the time-mean drag coefficient ( $\bar {C}_{D}$ ) of finite-span cylinders ( $\text {span/diameter} = \text {aspect ratio}$ , $0.51 \le AR \le 6.02$ ) freely rolling without slip on an inclined plane. While lubrication theory predicts an infinite drag force for ideally smooth cylinders in contact with a smooth surface, experiments yield finite drag coefficients. We propose that surface roughness introduces an effective gap ( $G_{eff}$ ) resulting in a finite drag force while allowing physical contact between the cylinder and the plane. This study combines measurements of surface roughness for both the cylinder and the plane panel to determine a total relative roughness ( $\xi$ ) that can effectively describe $G_{eff}$ at the point of contact. It is observed that the measured $\bar {C}_{D}$ increases as $\xi$ decreases, aligning with predictions of lubrication theory. Furthermore, the measured $\bar {C}_{D}$ approximately matches combined analytical and numerical predictions for a smooth cylinder and plane when the imposed gap is approximately equal to the mean peak roughness ( $R_p$ ) for rough cylinders, and one standard deviation peak roughness ( $R_{p, 1\sigma }$ ) for relatively smooth cylinders. As the time-mean Reynolds number ( $\overline {Re}$ ) increases, the influence of surface roughness on $\bar {C}_{D}$ decreases, indicating that wake drag becomes dominant at higher $\overline {Re}$ . The cylinder aspect ratio ( $AR$ ) is found to have only a minor effect on $\bar {C}_{D}$ . Flow visualisations are also conducted to identify critical flow transitions and these are compared with visualisations previously obtained numerically. Variations in $\xi$ have little effect on the cylinder wake. Instead, $AR$ was observed to have a more pronounced effect on the flow structures observed. The Strouhal number ( $St$ ) associated with the cylinder wake shedding was observed to increase with $\overline {Re}$ , while demonstrating little dependence on $AR$ .

Effect of Surface Roughness and Compressive Residual Stress on the Fatigue Performance of TC4 Titanium Alloy Subjected to Laser Shock Wave Planishing

ABSTRACTThe milled surface of TC4 titanium alloy was treated by laser shock peening (LSP) and laser shock wave planishing (LSWP) to investigate the effect of compressive residual stress (CRS) and surface roughness (SR) on the vibration fatigue performance. The results demonstrate that although the amplitude of CRS induced by LSWP is lower than that of LSPed specimens, the vibration fatigue life of LSWPed specimens increased by 63.78% due to a significant reduction in SR from Sa 14.1 μm to Sa 4.21 μm. When the SR is low, increasing the amplitude of CRS is more advantageous to enhance fatigue life. The fractographic analysis further confirmed that compared with LSPed and T0.2‐LSWPed specimens, T0.1‐LSWPed specimens have considerably less initial fatigue crack initiation, and the crack initiation location is deeper. The fatigue striation spacing of T0.1‐LSWPed specimens is the smallest (0.25 μm), greatly lowering the fatigue crack growth rate.

Scanning electron microscopy imaging of multilayer-doped GaN: Effects of surface band bending, surface roughness, and contamination layers on doping contrast

Dopant profiling by a scanning electron microscope possesses great potential in the semiconductor industry due to its rapid, contactless, non-destructive, low cost, high spatial resolution, and high accuracy characteristics. Here, the influence of plasma and wet chemical treatments on doping contrast was investigated for a multilayered p-n GaN specimen, which is one of the most promising third-generation wide bandgap semiconductors. Angle-resolved x-ray photoelectron spectroscopy and atomic force microscope were employed to characterize the degree of surface band bending, surface roughness, gallium oxides, and hydrocarbons on the surface of GaN. N2 and air plasmas were unable to remove the surface contamination layers, although the degree of surface band bending was suppressed. In contrast, wet chemical methods offer superior capability in removing contamination layers; however, the surface roughness was increased to varying degrees. Notably, NH4F solution is capable of improving the doping contrast. The underlying mechanism was elucidated from the perspective of surface band bending, surface roughness, and contamination. The findings reported here will provide a feasible solution for effective characterization of semiconductor materials and devices.

Effect of Surface Roughness on the Electrochemical Behavior and Corrosion Resistance of TiTaNbZrAg Alloy with Different Amounts of Tantalum in Bulk Composition.

The corrosion behavior of the TiTaNbZrAg alloys with different amounts of tantalum (0%, 10% and 20%) and with distinct surface topography (smooth and rough) was investigated in phosphate buffer solution (PBS) for long-time immersion (1000 h). By this approach, we expect to bring about new insights into the influence of both the amount of Ta in the alloy composition and the surface topography on the corrosion behavior of the Ti-based alloys. The corrosion resistance was studied by Open Circuit Potential (OCP), Potentiodynamic Polarization (PP), and Electrochemical Impedance Spectroscopy (EIS). From the potentiodynamic investigations, it was observed that all types of samples showed good corrosion resistance (i.e., Rcorr < 10 µm y-1) and may be used successfully for medical applications. However, the samples with smooth surfaces and with a certain amount of Ta (10% and 20%) exhibit the best corrosion performance (Rcorr < 1 µm y-1). As regards the samples with rough surfaces, the results evidenced that they showed lower corrosion resistance (1 < Rcorr < 3 µm y-1), suggesting that the Ta presence does not necessarily hinder the corrosion processes. Actually, the synergetic effect of both the presence of Ta and surface roughness plays an important role in corrosion resistance.

Two-Phase Flow Modelling Based on Roughness Surface Effect of Roller Compacted Concrete

One of the most important considerations that are interest to researchers on the stepped spillway in hydraulic structure is the location of the point at which the flow begins to transform into two phase-flow and the development of boundary layers. In this study, an unconventional rough surface was used (RCC materials), which has completely different properties from what is used in previous laboratory studies, which uses smooth surfaces in reality to represent the actual roughness of the surface. Benchmark mixes are evaluated as a reference standard concrete to determine the optimal combination proportions for RCC according to The U.S. Army Corps of Engineers Standard. A laboratory study of different models enhanced by a mathematical model CFD with VOF technics to described the two- phase interaction to investigate the location of the inception point and compare the results with the proposed equations assumed by different researchers in this topic. The results obtained from the study showed a clear effect of surface roughness on the location of the inception point and the formation of the boundary layer for laboratory models. It’s clearly found that the two-phase flow starts with closer locations than it is for conventional models and the ratios vary (10 % - 20 %) according to the discharge values (where the effect of surface roughness is evident in the low discharges compared to the high discharges in which the boundary Lear effect begins to fade.

Effect of surface roughness on the liquid bridge between two rigid spheres

We aimed to investigate the impact of surface roughness on liquid bridges between spherical particles. Sandblasting was used to control the particle size and produce glass beads and plates with different surface roughness. First, by measuring the advancing and receding contact angles of droplets on different rough surfaces, we analyzed the effects of surface roughness on wettability and hysteresis. Next, we used a custom-made liquid-bridge stretching device to measure the capillary forces of the liquid bridges between spherical particles with different surface roughness values. A charge-coupled device camera acquisition system was set up to capture the morphological changes of the liquid bridge during stretching, and Image View software was used to extract the morphological parameters of the liquid bridge. Theoretically, we reasonably simplified and solved the differential equations for the liquid bridge morphology and used the Young–Laplace equation to calculate the theoretical capillary force of the liquid bridge, providing an in-depth analysis of the influence of surface roughness on the capillary force. Finally, we studied the impact of surface roughness on the volume ratio of the liquid bridge during static stretching and the residual liquid remaining after the liquid bridge breaks. Experimental results indicated that, as the surface roughness increased, the hydrophobicity and wettability hysteresis of the solid surface also increased. The increased hydrophobicity of the surface reduces the solid-liquid contact area of the liquid bridges between the particles, making it easier to form “columnar” or “convex” liquid bridges. Additionally, the enhanced wettability hysteresis causes the solid-liquid contact boundary to lag during the stretching of the liquid bridge, resulting in a decrease in the solid-liquid contact angle. These factors directly alter the geometric shape of liquid bridges during static stretching, thereby affecting capillary forces. Meanwhile, the increase in surface roughness weakens the effect of gravity on the morphology of the liquid bridge, resulting in less liquid mass remaining on the lower sphere after the liquid bridge breaks as the surface becomes rougher.

Effect of Surface Roughness on Corrosion Resistance of Mooring Chains for Offshore Floating Photovoltaics

Effect of Surface Roughness on Corrosion Resistance of Mooring Chains for Offshore Floating Photovoltaics

A novel strategy for activation technique for 6H-SiC substrates in electroless Ni-P plating processes

This study proposes a novel iron wire activation method for electroless Ni-P plating on 6H-SiC substrates, offering a sustainable alternative to traditional metal activation techniques, focusing on the surface roughness effect on the microhardness and Ni-P plating efficiency of 6H-SiC substrates. This experimental approach reveals insights into the relationship between substrate morphology and plating characteristics. It is found that the plating thickness (33.82 μm) of the non-polished substrates closely matched the expected (33.26 μm), with a deposition rate of 6.65 μm/h, which underscores the precision regulation of the plating process. In contrast, despite the faster deposition rate of 9.20 μm/h of the polished S500 substrate, it exhibited a minor thickness discrepancy, suggesting a saturation point in the deposition dynamics on fully polished surfaces. The research additionally sheds light on the adhesion characteristics of the plated layers, particularly emphasizing the role of surface roughness. Remarkably, non-polished substrates demonstrated better adhesion, categorized as HF3, indicating a significantly stronger bond compared to the polished substrates, which were categorized as HF4 to HF6. This distinction in adhesion categories underlines the critical influence of substrate morphology on the quality of the Ni-P layer's adherence.

Mesoscopic coupled plasticity-damage model of rough surface considering size-dependent plasticity

Metallic materials exhibit significant size effect at mesoscopic scale have been revealed by many experiments. Thus, it is essential to consider size effect when conducting mesoscopic scale studies in tribology. However, there is no constitutive model considering both ductile fracture and size effects of rough surface in the literature. At the same time, the simulation of friction and wear at the mesoscopic scale suffer from computational inefficiency using the conventional theory of mechanism-based strain gradient (CMSG) plasticity theory. To address the aforementioned challenges, we propose a mesoscopic coupled plasticity-damage model by combining the coupled plasticity-damage model and the simplified CMSG plasticity theory. This model can take into account not only the effect of stress state, temperature, strain rate on plasticity and fracture, but also the effect of the effective plastic strain gradient. Meanwhile, the model is able to solve the effective plastic strain gradient by a simplified method, thereby enhancing the computational efficiency. Then, model parameters for bearing bushing material of an engine are calibrated. Finally, scratch simulation and scratch tests of bearing bushing material at the mesoscopic scale are conducted to validate the effectiveness of the mesoscopic constitutive model. The residual scratch depth and width, coefficient of friction at different normal loads are investigated by experiment and simulation, respectively. Results proved the effectiveness of mesoscopic coupled plasticity-damage model, which is applicable for investigating issues related to wear, friction, and contact.

Surface roughness effects on the propelling mechanism of spermatozoa

Surface roughness effects on the propelling mechanism of spermatozoa

Axial behaviour of steel pipelines buried in sand: effects of surface roughness and hardness

Surface roughness and coating hardness of underground pipelines are expected to play decisive roles in their axial pullout behaviour, which is an important aspect of pipeline design. Existing guidelines and previous studies underestimated or ignored these effects, resulting in potentially unsafe design. To address this problem, in the current study, nine large-scale physical modelling tests were conducted on pipes in dry and dense sand. Five steel pipes with varying normalised roughness (0·04–1·01) and coating hardness (32·6–59·0 HRA) were used and instrumented with a novel type of film-like piezoresistive sensors for measuring soil–pipe contact pressure. The measured pullout resistance of rough pipes is 2·70–2·85 times that of smooth pipes, significantly greater than the value specified in current design guidelines (i.e. 1·17 times). This substantial increase stems from an increase in interface friction coefficient (accounting for 72–79%) and a contact pressure increase induced by constrained dilation and soil arching (contributing the remaining 21–28%). Regarding coating hardness, a critical hardness was observed (around 35 HRA). Owing to equivalent roughness from particle embedding, pipes with hardness below this value exhibited similar behaviour to rough pipes. Finally, a new and simple method was proposed for calculating the pullout resistance with consideration of the effects of roughness and dilatancy.

Low cost modelling tools for the design of additively manufactured acoustic materials

Additive manufacturing (AM) methods have unlocked new capabilities in the design of acoustic materials and their topologies. This has enabled the design of devices with breakthrough performance in sound absorption and insulation while achieving subwavelength characteristics. However, material fabrication through AM presents its own challenges. These challenges include inherent defects which can be specific to the printing method employed. Examples of defects in low-cost AM include void formation, surface roughness and poor bonding between layers. Each of these features of AM have different acoustic impacts which may degrade the performance of a design. To optimize the production of additively manufactured acoustic materials it is imperative that designers can exploit features, such as surface roughness, to enhance rather than degrade the overall material performance. The aim of this paper is to investigate the effects of surface roughness in extrusion-based AM on acoustic material performance. A novel, low-cost numerical methodology is used to capture the influence of surface roughness in a subwavelength acoustic absorber. With this approach the impact of roughness can be captured in the design process. The intention is to develop efficient low-cost design methodologies that can be exploited for industrial development of novel additively manufactured acoustic materials.

Computational fluid dynamics investigation of pesticide spraying by agricultural drones

Precise control over pesticide spraying by agricultural drones requires fundamental research of multiphase flow, heat and mass transfer of liquid droplets in downwash flow. In this study, water was used as a carrier agent in pesticide formulations, in which the liquid droplets exhibit a Newtonian fluid behavior. A general computational fluid dynamics (CFD) model that characterizes propeller motion coupled with droplet evaporation and deposition was developed. The downwash flow generated by the propeller rotation was simulated using a multiple reference frame method along with the SST-k-ω turbulence model. Spraying of liquid droplets was simulated using a discrete phase model. The flow model validation was conducted by comparing the simulated velocities with experimental data, and the spray model validation was completed by a comparison of droplet depositions from CFD predictions and experiments. The results indicated that the droplet deposition fluctuates with an increase of propeller speed, and that both temperature and relative humidity affect the droplet deposition. In addition, the relation between the number of particles and the impact velocity was identified quantitatively, impact velocity with respect to particle diameter was predicted, and the effects of surface inclination, surface roughness, and crosswind speed on droplet deposition were analyzed. Moreover, an in-depth discussion about the intrinsic relation between downwash flow and droplet spraying was conducted.