Types Of Roughness Research Articles

Boundedness for commutators of rough p-adic fractional Hardy type operators

In this paper, we introduce the rough p-adic Hardy type operator and obtain the boundedness for its commutator generated by the p-adic CMO function on p-adic Herz-type spaces. Moreover, we establish the λ-central BMO estimates for the commutator of the rough p-adic fractional Hardy operator on p-adic central Morrey spaces.

Flow Regimes and Types of Solid Obstacle Surface Roughness in Turbulent Heat Transfer Inside Periodic Porous Media

Flow Regimes and Types of Solid Obstacle Surface Roughness in Turbulent Heat Transfer Inside Periodic Porous Media

Numerical Study of the Effects of Roughness Coupled with Inclination on a Turbulent Flow around an Obstacle

In this study, we simulate the cooling of a microprocessor by thermal convection in three different shapes: a square, a trapezoidal, and a triangular shape. The latter is improved by a variety of types of roughness, including square roughness, triangular roughness Type 1, triangular roughness Type 2, and triangular roughness Type 3. The microprocessors are kept at a constant temperature, the air flow is constant, and the geometry is fixed. The physical phenomenon is simulated by the ANSYS software. The numerical results reported in this study cover the ranges of the obstacle’s angle of inclination, 0°≤θ≤45°, (square obstacles, θ=0°, trapezoidal obstacles, 0°<θ<45°, triangular obstacles, θ=45°) and Reynolds number, 2500≤Re≤10,000. The findings relate to streamlines, dynamic pressure (max), mean velocity, temperature field, mean Nusselt number (Nu/Nu0) profiles, local coefficient of friction (Cf/f0), mean coefficient of friction (f/f0) profiles, mean velocity field with roughness, and fluid temperature field with roughness. The aim of the study is to show the interaction between the roughness parameter and the obstacle geometry. In the case of a triangular obstacle, the contact between the cold air and the obstacle is significant downstream of the obstacle, which gives us good cooling, and the Nusselt number has an important value because the agitation of the flow increases convective heat transfer, and the coefficient of friction is low because the air flow is uniform.

Fractal model of thermal contact conductance of micro-segment gear considering friction coefficient

Purpose The purpose of this study is to establish a fractal model of thermal contact conductance (TCC) of micro-segment gear considering friction coefficient. Design/methodology/approach The influences of friction coefficient, fractal dimension, fractal roughness and contact type on the TCC of the rough surface were studied by using numerical simulation. Findings The results show that with the increase of the friction coefficient, the TCC of the rough surface will decrease. As the fractal dimension increases or the fractal roughness decreases, the rough surface becomes smoother and the TCC becomes larger. Under the same load conditions, the TCC of the internal contact type is greater than that of the external contact type. In engineering practice, the desired TCC can be achieved by changing the contact type. Originality/value A fractal model of TCC of micro-segment gear considering friction coefficient was established in this study. The achievements of this study provide some theoretical basis for the investigation of the TCC of the gear.

Investigation of the Influence of Roughness and Dental Implant Design on Primary Stability via Analysis of Insertion Torque and Implant Stability Quotient: An In Vitro Study.

In the placement of dental implants, the primary fixation between the dental implant and the bone is of great importance and corresponds to compressive mechanical fixation that aims to prevent micromovement of the implant. The aim of this research was to determine the role of roughness and the type of dental implant (tissue-level or bone-level) in implant stability, measured using resonance frequency analysis (RFA) and insertion torque (IT). We analyzed 234 titanium dental implants, placed in fresh calf ribs, at the half-tissue level and half-bone level. The implant surface was subjected to grit-blasting treatments with alumina particles of 120, 300, and 600 μm at a projection pressure of 2.5 bar, resulting in three types of roughness. Roughness was determined via optical interferometry. The wettability of the surfaces was also determined. Implant stability was measured using a high-precision torquemeter to obtain IT, and RFA was used to determine the implant stability quotient (ISQ). The results show that rough surfaces with Sa values of 0.5 to 4 μm do not affect the primary stability. However, the type of implant is important; bone-level implants obtained the highest primary stability values. A good correlation between the primary stability values obtained via IT and ISQ was demonstrated. New in vivo studies are necessary to know whether these results can be maintained in the long term.

Vibration Response Law of Aircraft Taxiing under Random Roughness Excitation

Understanding the vibration response patterns of aircraft taxiing under runway roughness excitation is crucial for aircraft design and runway performance evaluation. In this paper, we establish pavement roughness models for both asphalt and concrete surfaces, taking into account their unique structural characteristics. We construct a six-degrees-of-freedom aircraft model using multi-rigid-body system dynamics theory and employ the pseudo-excitation method to examine the influence of pavement roughness types on the steady vibration response of aircraft taxiing at constant speeds. Furthermore, we analyze the non-stationary vibration response patterns of aircraft during takeoff and landing taxiing using the method of instantaneous frequency response function with space frequency. Lastly, we explore the effect of stochastic structural parameters on aircraft vibration response using the Monte Carlo method. Our findings reveal that the roughness power spectrum differs between asphalt and concrete pavements, and the established roughness models in this paper demonstrate a strong fit (R2 > 0.95). The type of pavement roughness has a relatively minor impact on the power spectral density distribution of the aircraft vibration response, suggesting that the same roughness model can be used for both asphalt and concrete pavements when high accuracy is not required. The power spectral density distribution of aircraft vibration response varies across different motion attitudes, with the vibration response during landing being significantly larger than that during takeoff. Among the aircraft structural parameters, the randomness of the sprung mass has the most substantial effect on the aircraft vibration response, potentially causing the variation coefficient of dynamic load on the front landing gear to exceed 0.11. Tire stiffness comes next, which can lead to the variation coefficient of dynamic load on the main landing gear reaching 0.07. The results have a guiding role in optimizing aircraft structure design and ensuring pavement performance.

Phenotypic and genetic features of a novel clinically isolated rough morphotype Candida auris.

Candida auris is a newly emerging pathogenic fungus of global concern and has been defined by the World Health Organization (WHO) as a member of the critical group of the most health-threatening fungi. This study reveals and reports for the first time that a rough morphotype C. auris strain causes urinary tract infections in non-intensive care unit (ICU) inpatients. Furthermore, the morphology, the scanning electronmicroscopy (SEM), Whole-genome resequencing and RNA sequencing of C. auris possessing rough morphotype colonies compared to their smooth morphotype counterparts. The newly identified phenotypic variation of C. auris appears round, convex, dry, and burr-like with a rough texture. SEM shows that rough type C. auris has a rough and uneven colony surface with radial wrinkles and irregular spore arrangement. Cells of the rough morphotype C. auris naturally aggregate into clusters with tight connections in the liquid, and it seems that the cell division is incomplete. A genome-wide analysis of the rough type C. auris confirmed its genetic association with the smooth type of C. auris prevalent in China (Shenyang) two years ago; however, single nucleotide polymorphism (SNP) mutations of five genes (ACE2, IFF6, RER2, UTP20, and CaO19.5847) were identified more recently. RNA-seq revealed IFF2/HYR3, DAL5, PSA31, and SIT1 were notably up-regulated, while multiple cell wall-associated genes (ALS1, MNN1, PUL1, DSE1, SCW11, PGA38, RBE1, FGR41, BGLI, GIT3, CEP3, and SAP2) were consistently down-regulated in rough morphotype C. auris. The rough phenotypic variation of C. auris is likely to be related to the structural and functional changes in cell wall proteins. This novel rough morphotype C. auris will provide a basis for further studies concerning the evolutionary characteristics of C. auris.

Influence of interface roughness and rock type on mixed mode fracture characteristics of tunnel shotcrete-rock interface

A four-point shear (FPS) test was conducted to investigate the mixed mode fracture characteristics of the shotcrete-rock interface. Real-time monitoring of the fracture process was achieved using acoustic emission (AE) and digital image correlation (DIC) techniques. The mechanical test results indicate that residual stress increases with modal Angle or roughness under the same crack mouth opening displacement (CMOD). As the modal angle increases, the crack morphology and damage mechanism of the granite-shotcrete interface change. For large modal angles, the crack expands into the granite during the expansion process, leading to a larger range of granite damage at the interface. The results obtained through the nearest neighbor method reveal that specimens with small mode angle, low roughness or weak material properties on one side do not exhibit obvious background events, whereas the cluster characteristics of density distribution are evident. The AE events with smaller nearest neighbor distances were found to be concentrated around the macroscopic cracks. Moreover, the modal angle was observed to have a significant impact on crack opening/sliding displacement, with crack mouth sliding displacement (CMSD) and crack tip sliding displacement (CTSD) both increasing significantly as the modal angle increases.

Correlation between magnetic resonance images of peritumor margin enhancement and prognosis in hepatocellular carcinoma after drug-eluting bead transcatheter arterial chemoembolization.

The aim of this study is to investigate the morphological characteristics and clinical significance of magnetic resonance (MR) images of peritumor margin enhancement in hepatocellular carcinoma (HCC) after drug-eluting bead transcatheter arterial chemoembolization (DEB-TACE). From January 2017 to December 2020, a total of 162 patients who received a diagnosis of HCC were included in our study. We began the follow-up with magnetic resonance imaging (MRI) for complete response assessment, and peritumor margin enhancements were classified as sharp and rough types according to morphology. During the follow-up, data such as progression or remission of the two enhancement modalities, morphological changes in terms of margin enhancements observed in MR images, and alpha-fetoprotein (AFP) levels were recorded. In the follow-up period of 36 months, 70 and 92 patients with sharp- and rough-type peritumor margins, respectively, were observed. At the end of the follow-up, patients with sharp-type margins had lower AFP levels and longer progression-free survival than those with rough-type margins (P < 0.05). Furthermore, the sharp-type margin was thinner than the rough-type margin (all P < 0.05). Moreover, the sharp-type group had a high incidence of tumors with a diameter of < 5cm, whereas the rough-type group had a high incidence of tumors with a diameter of ≥ 5cm. Continuous enhancements of peritumor margins in MRI were greater in the sharp-type group than in the rough-type group. Most of the patients with a sharp-type margin achieved disease remission (94.3%, P < 0.05), whereas most of those with a rough-type margin experienced disease progression (84.8%, P < 0.05). Patients with HCC with a sharp-type margin enhancement on MRI after DEB-TACE mostly demonstrated benign lesions with a good prognosis, whereas those with a rough-type margin mostly demonstrated malignant growth.

Surface roughness analysis for improving punching tools performance of 5754 aluminium alloy

The use of lightweight materials in the automotive industry, as a key element in fuel economy, is a growing trend to meet the global emissions reduction agreement. Aluminium, in the form of stamped sheet, has the potential to be used extensively in vehicle as a high-specification structural and skin parts. However, compared to steel, aluminium is more difficult to stamp, thus the optimized techniques and manufacture strategies learned in steel stamping are not adequate given the complex processability of aluminium alloys. To achieve the quality standards, it is necessary to optimize aluminium stamping processes by developing specific techniques, geometries, and functional surfaces on tooling. In this work, the influence of tool geometry and surface roughness, as well as the use of lubricant during the punching process of 5754 aluminium sheets have been evaluated in a pilot plant under similar industrial conditions. Before the pilot plant test, different tool surface roughness qualities were evaluated at lab scale using a ball on disc test. Subsequently, performance of coated tools was evaluated through “coated ball” on “5754 aluminium disc” tests. The best combination between lubricant and coating was used to perform the aluminium punching process in the pilot plant, where two types of geometry and roughness of tool were analysed. Results were expressed in terms of aluminium adhesion on tool surface. Polished surface before coating deposition and geometry punches were the key factor to improve the process.

Continental-scale wetland mapping: A novel algorithm for detailed wetland types classification based on time series Sentinel-1/2 images

Wetlands have suffered from considerable degradation due to anthropogenic and natural disturbances in recent decades. Although some advancements have been made, effective methods that can produce large-scale wetland maps with detailed categories are still lacking due to the diversity and complexity of wetland ecosystems. To address this issue, we developed a novel algorithm for detailed wetland types classification integrating k-fold random forest and hierarchical decision tree, and so named two-step classification algorithm. Firstly, the phenology-based features were composited based on time series Sentinel-1/2 images, and the k-fold random forest was used to extract five rough wetland types in Google Earth Engine platform. Secondly, the hierarchical decision tree designed based on geometric features was used to separate the rough wetland types into fourteen detailed types. Application of the two-step classification method in Northern, Central and Southern Asia (NCSA) resulted in a continental-scale wetland map with an overall accuracy of 90.0 ± 0.5%. Wetland types, including inland marsh, lake, river, coastal swamp, estuarine water, lagoon, shallow marine water, reservoir, canal/channel and agricultural pond, had good accuracy with both UA and PA over 77%. The remaining wetland types had moderate accuracy, with both UA and PA over 58%. As we calculated, total wetland areas of NCSA were 1,375,489.27 km2. Among the fourteen wetland categories, the inland marsh had the largest area (544,584.38 km2) and was primarily distributed in subarctic and humid continental climates, while the canal/channel had the smallest area (1,651.57 km2) and was primarily scattered in desert, semiarid and humid subtropical climates. The lake and floodplain shared generally large areas with value of 392,413.55 km2 and 173,255.71 km2 respectively, which were typically distributed across desert and semiarid climates. This study successfully mapped continental-scale wetlands with detailed categories at a 10-m spatial resolution, which can provide valuable information for the management of wetland ecosystems and facilitate the implementation of wetland-related sustainable development goals.

Textured Epoxy-Coated Rebars: Physical, Structural, and Empirical Characterization

Although the traditional epoxy coating represents an effective corrosion protection system, it has the disadvantage of making bridge decks more susceptible to cracking. This phenomenon occurs because its smooth surface reduces the bond with the concrete and, therefore, increases the radial components of the force-transferring mechanism. To try to mitigate these problems, the Illinois Department of Transportation developed the textured epoxy-coated (TEC) reinforcement, which possesses a roughened surface and, in recent years, has been the subject of study at the University of Illinois Urbana-Champaign, in the U.S. Particularly, this experimental program explores, complements, and compares the physical and bond-slip characteristics of the TEC rebars developed hitherto. From the physical characterization, different parameters are measured on the textured surfaces to obtain a numerical comparison of each roughness type. Also, determining the adhesion strength and thickness of the textured coating reveals that it provides similar corrosion protection to the traditional approach while keeping its integrity on the steel substrate. The bond-slip characterization, in turn, was done using pull-out tests and, by combining these results with the microstructure examination of TEC bars, it is found that the absence of texture voids is related to the degradation of the slip resistance. Furthermore, through a finite element model, the development length of the TEC reinforcement is estimated and compared with the values calculated according to current standards. Finally, given the complexity of obtaining the surface parameters of the coating, an empirical, weight-based approach is developed for the TEC bars as a rapid method for assessing their roughness.

Visuelle Kommunikation von Fahrradrouten mittels kartographischer Symbolisierung

ZusammenfassungMit zunehmender Förderung nachhaltiger Mobilitätsformen im Rahmen der Verkehrswende stellt das Fahrrad eine umweltfreundliche Alternative zum motorisierten Individualverkehr dar - insbesondere zur Bewältigung innerstädtischer Wege. Im Gegensatz zu Autofahrenden hängt der empfundene Fahrkomfort und das Sicherheitsempfinden von Radfahrenden jedoch stark von Routenmerkmalen wie der Oberflächenbeschaffenheit oder der Verkehrsinfrastruktur ab. Aktuell verfügbare Systeme zur Fahrradnavigation berücksichtigen diese für die Routenwahl von Radfahrenden relevanten Faktoren jedoch kaum und die Visualisierung beschränkt sich vielfach auf eine einfache Hervorhebung der empfohlenen Route. In dieser Arbeit wird daher untersucht, inwieweit sich verschiedene kartographische Darstellungsvarianten für Fahrradrouten zur visuellen Kommunikation der Routenmerkmale Art des Untergrunds, Untergrundrauigkeit, Geländeneigung und Fahrtunterbrechungen, als angemessen erweisen. Im Rahmen einer Nutzerbefragung wird die Effektivität, Attraktivität, Eignung und Entbehrlichkeit einer Legende der verschiedenen Darstellungsvarianten für die unterschiedlichen Routenmerkmale überprüft. Die Ergebnisse der Umfrage zeigen auf, dass viele der vorgeschlagenen Visualisierungsvarianten angemessen für die visuelle Kommunikation von Fahrradrouten sind. Dies betrifft insbesondere Farbdarstellungen sowie Darstellungen mit Symbolen oder Signaturen. Hinsichtlich der getesteten Fahrradroutenmerkmale hängt die angemessenste Darstellung jedoch stark von der zu kommunizierenden Information ab. Die Erkenntnisse dieser Studie sollen zur Entwicklung von speziell auf die Bedürfnisse der Radfahrenden zugeschnittenen Routenvisualisierungen beitragen und somit Entwicklern von Fahrradnavigationssystemen bei Designentscheidungen unterstützen.

Failure Strength of Automotive Steering Knuckle Made of Metal Matrix Composite

This article presents the static performance of composite steering knuckle due to drive on an equivalent road, including different types of roughness and maneuvers. To achieve this purpose, the driving of a full-vehicle model was simulated using the multi-body dynamics (MBD) method, and the imposed loads on connection points of the steering knuckle to different components of the suspension system were extracted considering various maneuvers. Next, CATIA software was used to prepare a smooth model of the steering knuckle by employing coordinate measuring machine (CMM) data. Stress analysis was performed under the maximum value of the loading history in finite element (FE) software. Eventually, the safety factor was calculated based on some well-known criteria for static failure of the composite materials. Moreover, the optimum value of tungsten carbide as a reinforcing substance in aluminum composite was estimated to increase failure strength. The results show that an increase in tungsten carbide leads to an increase in the strength of the steering knuckle under purely axial loads (normal stress criterion) and also that an increase in this substance leads to a decrease in the strength of the part under shear loads (shear stress criterion). Therefore, based on the nature of the loads (i.e., multi-axial non-proportional random amplitude loading conditions) applied to the automotive steering knuckle due to actual conditions, this metal matrix composite (aluminum matrix and tungsten carbide as reinforcement) is not practical.

Interaction of Tryptophan- and Arginine-Rich Antimicrobial Peptide with E. coli Outer Membrane-A Molecular Simulation Approach.

A short antimicrobial peptide (AMP), rich in tryptophan and arginine (P6-HRWWRWWRR-NH2), was used in molecular dynamics (MD) simulations to investigate the interaction between AMPs and lipopolysaccharides (LPS) from two E. coli outer membrane (OM) membrane models. The OM of Gram-negative bacteria is an asymmetric bilayer, with the outer layer consisting exclusively of lipopolysaccharide molecules and the lower leaflet made up of phospholipids. The mechanisms by which short AMPs permeate the OM of Gram-negative bacteria are not well understood at the moment. For this study, two types of E. coli OM membrane models were built with (i) smooth LPS composed of lipid A, K12 core and O21 O-antigen, and (ii) rough type LPS composed of lipid A and R1 core. An OmpF monomer from E. coli was embedded in both membrane models. MD trajectories revealed that AMP insertion in the LPS layer was facilitated by the OmpF-created gap and allowed AMPs to form hydrogen bonds with the phosphate groups of inner core oligosaccharides. OM proteins such as OmpF may be essential for the permeation of short AMPs such as P6 by exposing the LPS binding site or even by direct translocation of AMPs across the OM.

Contact Fatigue Resistance of Gun Barrel Steels

Structural steels can be used to produce barrels, due to their good properties. During the working cycle, steels are exposed to aggressive conditions such as thermal stress, fatigue, and wear. In this paper, two steels were selected, namely 30CrNiMo8 and 42CrMo4, which were abraded with a G40 ball bearing. All measurements were performed on a UMT TriboLab universal tribometer. The main goal of the experiment was to analyze and compare the wear of tool steels in contact with a bearing ball with a diameter of 4.76 mm. Experimental materials will be processed for three types of roughness. Both types of experimental steels were measured after the final heat treatment (hardening + tempering). The main goal of the paper was to determine how different technological surface treatment of the material will affect the abrasion resistance, and thus the life of these main materials at the point of contact with the projectile. The experiment shows that 30CrNiMo8 steel has at least the same coefficient of friction (COF) with respect to all measurement parameters. In contrast, the second investigated steel, 42CrMo4, showed a decreasing COF due to the increasing roughness of the measurement. The friction mechanism was subjected to adhesive wear on both steels. The wear of both steels at roughnesses Sa12.5 and Sa 6.3 showed the same values. With a finer roughness of Sa 3.6, 42CrMo4 steel showed 50% lower wear values.

Thermal and Surface Roughness Effects on Performance Analysis of Slider Bearing via Petrov–Galerkin Finite Element Method

In this study, the performance of slider bearing with impacts of temperature and roughness of surface on 1D longitudinal and transverse roughness type is investigated using the Streamline Upwind Petrov–Galerkin (SUPG)-finite element method (FEM). It is considered that the roughness is stochastic and Gaussian in random distribution. It is also considered that viscosity and density depend upon temperature. The domain’s irregularity caused by surface roughness is changed into a regular domain for numerical computation purposes. To determine the capacity of load-carrying and pressure distribution, the continuity, momentum, modified Reynolds, and energy equations are decoupled and solved by the SUPG-FEM. It can be demonstrated that in the case of the longitudinal model of nonparallel slider bearing, the load-bearing bearing capacity and drag force of friction due to the case i of the combined effects are lower than those attributable to the influence of surface roughness. Nevertheless, the thermal case’s impact on the 1D transverse type capacity of load-carrying capability and drag friction force is below that of the combined and surface roughness impact instances. The reverse is true for parallel slider bearings, however, for a 1D transverse type, the load-carrying ability is not particularly impressive.

Effect of different molecular weights of polyethylene glycol as a plasticizer on the formulation of dry powder inhaler capsules: Investigation of puncturing size, morphologies, and surface properties

Today, the principle of research and development is pulmonary drug delivery due to the potential for maximizing therapeutic effects for patients by direct drug targeting the pathology site in the lungs. Amongst the convenient delivery alternatives, the Dry Powder Inhaler (DPI) is the preferred device to remedy a variety of diseases. In this regard, the fabrication and development of a novel formulation for DPI capsules have been studied. We investigated the effects of various parameters, such as percentages of polyethylene glycol (PEG), propylene glycol (PG), glycerol (Gly), brittleness, test conditions, and particle release of manufactured DPI capsules. The efficacy of each parameter was evaluated in detail to understand and address the consequences of the mentioned factors. The results illustrated that the lower molecular weight of PEGs presented the better plasticizing capability of gelatin. Owing to the hygroscopicity of the utilized plasticizer, polyethylene glycol 400 (PEG 400) increased the capsule flexibility for a longer time and its stability under environmental conditions in the gelatin capsule formulation. Likewise, no particle release was observed in the gelatin/PEG capsule. The prepared gelatin/PEG400 capsules were compared with pure gelatin and HPMC capsules. The capsules were evaluated in terms of loss on drying (LOD), surface morphology, roughness, and puncture type. The results show that using PEG-400 can lead to the production of capsules that have low moisture content and minimal interaction with APIs. In addition, gelatin/PEG capsules have no particles due to the smooth surface after the punching process. The as-produced capsules are not blocked again after punching, allowing the patient to take the drug completely. In fact, the present research provided substantial insight regarding the development of DPI formulation in capsule investigations on an industrial scale.

Heat Transfer Enhancement in Stirling Engines Using Fins with Different Configurations and Air Flow

The Stirling engine, in comparison to other classical engines, is an external enclosed heat engine cycle with extraordinary theoretical efficiency and minimal emissions. However, when combined with a minor heat source, the productivity of the Stirling engine suffers. Thus, this study emphasizes research on improving engine performance using heat transfer. A simulation was done using CFD analysis in ANSYS Fluent to enhance heat transfer using different types of fins, air blowers, and roughness. κ-ω SST model was used as the turbulence model to capture the heat transfer behavior near and away from the surface. All runs showed a higher heat transfer rate per unit area than the no finned case. Increasing the number of fins reduces the heat transfer by 10 %, Applying this solution would cost more since more material is needed to decrease the gap between fins. When doubling the length of the fin, the heat transfer of the circular design was reduced by 1%, the pinned design by 5%, and the squared design by 30%. The addition of fins reduced the flow of heat to the cold end and kept the temperature near the cold end below 100°C. Increasing the roughness resulted in a small increase in heat flow. Comparing the laminar flow to the transitional flow, the transitional flow increases the heat transfer by 1000%.

Roughness effect modelling for wall resolved RANS – Comparison of methods for marine hydrodynamics

This paper deals with several aspects of surface roughness modelling in RANS codes applied to full-scale ship simulations. To select a method that is suitable for wall-resolved RANS solvers and gives reliable results at high Reynolds numbers, five different roughness models are compared. A grid uncertainty analysis is performed and the sensitivity to the grid resolution close to the wall (y+) is investigated. The results are compared to extrapolated results of experiments carried out with rough plates with various heights and roughness types. A correlation factor between the Average Hull Roughness and the equivalent sand roughness height is investigated, and a value of five is deemed the most suitable. The work suggests that the Aupoix-Colebrook roughness model gives the best results for full-scale ship simulations, at least with the current code, and that the near-wall grid resolution required for smooth surfaces can be applied also for the rough case.