Dimpled Surface Research Articles

Numerical study of turbulent flow and heat transfer in a novel design of serpentine channel coupled with D-shaped jaggedness using hybrid nanofluid

This study aimed to examine numerically the effects of a dimpled surface over a mini-channel heat exchangeron the flow characteristics and heat transfer across a serpentine channel with a uniformrectangular cross-section. The dimples were arranged in parallel with a spanwise (y/d) distance of 3.125 and streamwise (x/d) distance of 11.25 along just one side of the serpentine channel's surface.Turbulent flow regime with Reynolds number ranging from 5 × 103 to 20 × 103 in the channel with the surface modificationwas studied using water and various volume concentrations(φ = 0.1%, 0.33%, 0.75%, 1%) ofAl2O3-Cu/waterhybrid nanofluid as the coolant to achieve a three-step passive heat transfer enhancement. Applying the Finite Volume Method (FVM), RNG k-e turbulence model, and a constant heat flux of 50 kW/m2, simulations were run assuming the mixture of Al2O3-Cunanoparticles homogenous using ANSYS 2020 R1. The second-order upwind approach is used forapproximation of solution and discretizationwith SIMPLE pressure–velocity coupling. Taking heat transfer increment and pressure drop penalty into consideration,the dimpled serpentine channel provides a 1.47-times improvement in thermal efficiency using water as the coolant, andthe dimpled channel with 1% vol.Al2O3-Cu/water nanofluid enhanced thermal efficiency by a remarkable maximumof 2.67-times at Re 5 × 103. The study also indicates that thermal efficiency increased with an increasing volume concentration of the nanofluid and increment in thermal efficiency gradually decreased as the Re increased.

Effects of golf ball dimple surface occupancy, volume ratio and depth on aerodynamic characteristics during rotation

For golfers, the length of the flight distance is very important for improving scores. Therefore, the surface of a golf ball is provided with innumerable dents called dimples to improve the flight distance. These dimples can be characterized by the dimple occupancy and dimple volume ratio. Therefore, we manufactured model balls in which the dimple occupancy was changed by the dimple diameter and the number of dimples, and the dimple depth was changed to change the dimple volume ratio. Fifteen model balls were designed using 3D CAD and then 3D printed. Using these balls, we carried out lift and drag measurements in wind tunnel experiments. Then, a flight trajectory simulation was performed based on the obtained experimental results, and the effects of the dimple occupancy and dimple volume ratio on the flight distance were elucidated. In rotating golf balls, when the dimple depth was shallow, i.e., D/d = 4.55 × 10–3, and the occupancy ratio was 80% or higher, the lift-drag ratio was higher, and the flying distance was increased. However, when the dimple depths were D/d = 6.82 × 10–3 and D/d = 9.09 × 10–3, there was almost no effect of the occupancy ratio. Furthermore, when comparing these two depths, the lift-drag ratio was bout 15% lower for deeper dimples. With respect to the dimple volume ratio, the drag coefficient increased with increasing dimple volume ratio. The lift-drag ratio was also highest in the dimple volume ratio range of 11.0–12.0 × 10–3.

The Effect of Atmospheric Chloride Ions on the Corrosion Fatigue of Metal Wire Clips in Power Grids

Corrosion fatigue is an important factor that limits the life of grid materials including wire clips. In order to study the effect of corrosion fatigue and to select suitable grid steels, this paper focuses on the corrosion fatigue properties of Q235 carbon steel, Q235 galvanized steel, and 316L stainless steel in the corrosive environments of air, 2wt% NaCl, 5wt% NaCl, and 8wt% NaCl. Through the fatigue test in the corrosive environment, and the surface morphology scanning and microstructure observation of the fracture, the following conclusions are drawn: the three materials are more susceptible to corrosion fatigue in the Cl− environment, and the higher the Cl− concentration, the greater the likelihood of fracture caused by corrosion fatigue for these three materials. By analyzing the surface roughness, dimples, and cracks in the microstructure, it is found that 316L stainless steel is highly sensitive to Cl− corrosion under cyclic stress, and Q235 galvanized steel is more resistant to Cl−. By plotting the stress fatigue life curve of Q235 galvanized steel, it is found that the corrosion fatigue life decreases as the Cl− concentration increases. For wire clips in areas with severe Cl− pollution, Q235 galvanized steel should be selected to achieve the best anti-corrosion fatigue effect; at the same time, the original parts should be repaired or replaced in a timely manner based on the predicted corrosion fatigue life.

A Numerical Study on Swirling Hot Air Anti-Icing with Various Surface Structures on the Internal Wall

Swirling hot air is a promising heat transfer enhancement technology for anti-icing applications in aircrafts, where the swirling flow is accompanied by pretty high turbulence and a quite thin boundary layer. It is of interest to investigate the compound heat transfer characteristics of the swirling air configuration combined with surface structures on the internal wall. This paper carries out a series of numerical computations to obtain the Nusselt number and pressure loss data in such a swirling air heat transfer system with four kinds of surface structures (trenches, ribs, dimples and bulges) on the wall and with different tangential inlet jets placed along the tube. At a tube Reynolds number from 10,000 to 50,000, the results show that the surface dimples and bulges are conducive to improving the Nusselt number, but the surface trenches and ribs show a Nusselt number deterioration relative to the smooth swirl tube. Among the four investigated surface structures, the surface bulges perform best, which can enhance the Nusselt number by up to 15.0%, increase the total heat transfer quantity by up to 17.3% and reduce the hot air pressure loss by up to 15.6%. Furthermore, the circumferential velocity distribution and swirl number are introduced to describe the flow fields. The surface trenches and ribs lead to less of a reduction in the circumferential velocity and swirl intensity, while the surface dimples and bulges could significantly suppress the in-tube swirl intensity.

Experimental and numerical investigation into the drag performance of dimpled surfaces in a turbulent boundary layer

Although several previous studies have reported a potential drag-reducing effect of dimpled surfaces in turbulent boundary layers, there is a lack of replicability across experiments performed by different research groups. To contribute to the dialogue, we scrutinize one of the most studied dimple geometries reported in the literature, which has a dimple diameter of 20 mm and a depth of 0.5 mm. There is no general consensus in literature on the drag-reduction performance of this particular dimple geometry, with some studies suggesting a drag reduction, while others report a drag increase. The present combined experimental and numerical study comprises two sets of wind tunnel experiments and a well-resolved large-eddy simulation. The wind tunnel experiments and the large-eddy simulation both depict a total drag increase of around 1%–2% compared to the flat reference case. This finding agrees with a recent study by Spalart et al. (2019). Furthermore, the present wind tunnel experiments have shed light on a plausible reason behind the discrepancy between the study by Spalart et al. (2019) and earlier results from van Nesselrooij et al. (2016). Lastly, the large-eddy simulation results reveal that the pressure drag is the main contributor to the increase in the total drag of the dimpled surface. We believe that these results will contribute to a new consensus on the drag performance of this dimple geometry.

Development Trend of Cooling Technology for Turbine Blades at Super-High Temperature of above 2000 K

Aeroengines and heavy-duty gas turbines are the core power equipment in the field of national defense and energy. Their research and development (R&D) level and manufacturing level represent the status of a country’s heavy industry in the world. The common cooling technologies of turbine blades including impingement cooling, film cooling, effusion cooling, layer cooling, pin fin cooling, and rough ribs were introduced in this paper. With the continuous improvement of the efficiency and performance of aeroengines and gas turbines, the turbine inlet temperature increases gradually every year; turbine blades will be exposed to higher gas temperatures in the future as gas temperatures break 2000 K. In order to ensure the safe operation of turbine blades under severe super-high temperature working conditions, cooling technology must be developed emphatically. This paper first reviews the research status of turbine blade cooling technology and points out future research focuses. The development trends of next-generation turbine blade cooling technology for above 2000 K temperature are summarized from several aspects: the innovative excavation of high-efficiency composite cooling configuration, multi-objective cooperative cooling structure and optimization design based on 3D printing, composite cooling structure design and optimization based on an artificial intelligence algorithm, tapping the cooling potential of new cooling media and heat pipes, integrated thermal protection with new thermal insulators, and the application of low-resistance and high-efficiency surface dimple cooling. The summary of this paper can provide a reference for the researchers of turbine blade cooling technology.

Electrically Manipulated Vapor Condensation on the Dimpled Surface: Insights from Molecular Dynamics Simulations.

Random vapor nucleation leads to flooding condensation with degraded heat-transfer efficiency. Since an external electric field has a significant effect on manipulating droplets' motion, it is possible to be one of the effective methods to hinder flooding phenomena and improve the heat-transfer rate by applying the external electric field during condensation. However, the motion of nanodroplets is more sensitive to the electric field owing to the scale effect on the nanoscale. The effect of the electric field on growth has not explicitly been comprehended. This work studied the condensation processes on a nanodimpled surface under an electric field with various strengths and directions. The results showed that condensed droplets' growth under the electric field depends on the competition between the electric field force and solid-liquid interactions. Increased vertical electric field strength, the higher torsion by the electric field hindered the motion of vapor, decreased the collision frequency for water molecules with the cooled surface, and elongated the cluster when the electric field force dominates, thus deteriorating the condensation performance. While applying the horizontal electric field, the greater electric field strength leads to better condensation performance by the larger contacting area for heat exchange. A wetting transition induced by the electric field was observed when the electric field strength increased to a certain extent (E > 5.2 × 108 V/m in this study). When the V-shaped surface replaced the dimpled surface as the condensed substrate, the same wetting transition phenomena occurred under a more significant horizontal electric field strength, showing that this method is universal. Besides, different electric field frequencies influenced both the growth and the nucleation, thus exhibiting various condensation performances.

Nucleation of water vapor on nanodimpled surfaces: Effects of curvature radius and surface wettability

• The effects of dimple curvature radius and wettability on nucleation are studied. • Surface potential energy analysis confirms nucleation sites. • Increasing dimple curvature radius worsens nucleation. • More dimples increase vapor nucleation probability at lower surface subcooling. • The coupling effect of the surface structure affects the nucleation. The mechanisms of vapor nucleation on nanostructured surfaces, whose geometrical characteristic sizes are comparable to those of nuclei, remain unsatisfactorily explored. This study investigates the correlations among the wettability, dimple curvature radius, and nucleation characteristics of vapor molecules on nanodimpled surfaces through molecular dynamics simulations. The surface potential energy analysis demonstrates that nucleation sites are located in the interior of dimples. With an increase in surface hydrophobicity or dimple curvature radius, a higher nucleation energy barrier would render nucleation more difficult. The critical sizes of nuclei obtained from MD simulation are larger than the results estimated by the classical nucleation theory. The discrepancy is attributed to the fact that the formed nucleus in simulations deviates from the spherical cap assumption. The formation of nuclei is not observed at all dimples, indicating that the coupling effects of surface structure would affect nucleation. Additionally, the comparisons of coalescence phenomena noted for different dimple numbers reveal the benefits of increasing the dimple number, which can be attributed to the fact that more high-energy nucleation sites increase the nucleation probability of vapor molecules at reduced surface subcooling. Therefore, an enhanced condensation performance can be achieved by artificially controlling the dimple number.

The Proposition of Using Dimpled Surface Vibratory Conveyors in Confectionery Industries for Product Movement

The confectionery business in the overall food and beverage sector has been gaining popularity and growing at an exponential rate, with many new companies entering the market to embrace the untapped market and supply customers with higher quality products like gum, chocolate, chilling plates, candy, gummy candy, enrobers, etc. One of the significant challenges faced by all the companies in this sector is to manage the movement of the product, whether bulk or packaged, from one part of the production line to the other effectively and efficiently. Various companies traditionally rely on conveying systems procured from Original Equipment Manufacturers (OEM) or designing them in-house to fulfill this requirement. The capital investment in these conveying systems was kept to a minimum in the past as they were not considered critical to day-to-day operations. However, there has been a shift in the business strategy, and nowadays, companies do extensive research and allocate significant capital to deploy an effective and efficient conveying system to support their production. In this theoretical study, we explore different available conveying technologies used in confectionery companies and their challenges in dayto-day operations. We also review a new and upcoming technology of using a vibratory conveying system with a dimpled surface texture of the conveyor itself to support gentle handling of the product and how it is advantageous over the traditional conveying system. This study aims to aid confectionery companies in identifying and selecting the most effective and efficient conveying solution for their production lines to move products within the facility

Fabrication of oxide-free dimple structure on germanium via electrochemical jet machining enhanced by opposing laser irradiation

The electrochemical machining (ECM) of germanium (Ge) wafer can be significantly improved in terms of efficiency and localization by introducing laser irradiation. However, residual oxide particles usually exist when using neutral electrolyte. In this study, the NaNO3 electrolyte jet is formed via a cathodic nozzle and impacts perpendicularly on the bottom of the Ge wafer, at which position the nanosecond (ns) laser irradiates from opposing side to locally and precisely enhance the electrical conductivity. In this way, the dimple structure without any detectable oxidation products can be efficiently fabricated. Characterization of surface morphology is then amply conducted. The radial lines consisting of regular micro-waving structure are usually noticeable, especially near the dimple edge, which may be attributed to the rapid and radial electrolyte flow along the concave sidewall. In contrast, irregular corrugated pattern can be observed near the dimple center, which may be caused by the electrolyte turbulence after impingement. In addition, parametric experimental study has been carried out, and the effects of the applied voltage, laser power and electrolyte concentration on the dimple profile and surface characteristics have been respectively detailed discussed. Finally, simulation study of the electrolyte flow field is conducted to reveal the distribution regularities of velocity and pressure, to deepen the understanding of formation mechanism of the complex surface morphology.

Cartilage-inspired surface textures for improved tribological performance of orthopedic implants

Joint replacements have become one of the most common orthopedic procedures due to the significant demands of retaining functional mobility. While these procedures are of great value to patients, there are some limitations. Durability is the most important limitation associated with joint replacement that needs to be addressed due to the increasing number of younger patients. Titanium is a commonly used implant material which has high biocompatibility, high strength-to-density ratio, and high corrosion resistance. However, current titanium implants have poor wear resistance which shortens their lifespan. In this study, microscale dimples with four different dimple shapes (circular, triangular, square, and star) of similar sizes to the pores found in natural articular cartilage were fabricated on titanium disks to improve implant lubrication and reduce wear. Biotribology tests were performed on dimpled and non-dimpled titanium disks in a condition similar to that inside of a patient's body. It was shown that dimpling the titanium disks optimized the lubricant film formation and decreased the wear rate significantly while also reducing the coefficient of friction (COF). The star-shaped dimples had the lowest COF and almost no detectable wear after 8 h of testing. To investigate whether dimpling increased bacterial colonization due to increased surface area, and to determine whether any increase could be limited by coating with antibacterial materials, bacterial colonization with Staphylococcus aureus was tested with non-dimpled and star-shaped dimpled titanium disks with and without coating with polydopamine (PDA), silver (Ag) nanoparticles (NPs), and PDA + Ag NPs. It was found that dimpling did not increase bacterial colonization, and that coating with PDA, Ag NPs, or PDA + Ag NPs did not decrease bacterial colonization. Nevertheless, we conclude that star-shaped dimpled titanium surfaces have potential utility as more durable orthopedic implants.

Growth of Highly-Ordered Metal Nanoparticle Arrays in the Dimpled Pores of an Anodic Aluminum Oxide Template.

A reliable, scalable, and inexpensive technology for the fabrication of ordered arrays of metal nanoparticles with large areal coverage on various substrates is presented. The nanoparticle arrays were formed on aluminum substrates using a two-step anodization process. By varying the anodization potential, the pore diameter, inter-pore spacing, and pore ordering in the anodic aluminum oxide (AAO) template were tuned. Following a chemical etch, the height of the pores in the AAO membrane were reduced to create a dimpled membrane surface. Periodic arrays of metal nanoparticles were subsequently created by evaporating metal on to the dimpled surface, allowing for individual nanoparticles to form within the dimples by a solid state de-wetting process induced by annealing. The ordered nanoparticle array could then be transferred to a substrate of choice using a polymer lift-off method. Following optimization of the experimental parameters, it was possible to obtain cm2 coverage of metal nanoparticles, like gold and indium, on silicon, quartz and sapphire substrates, with average sizes in the range of 50-90 nm. The de-wetting process was investigated for a specific geometry of the dimpled surface and the results explained for two different film thicknesses. Using a simple model, the experimental results were interpreted and supported by numerical estimations.

Cooling ability of smooth and dimpled surfaces

Reliable cooling of electronic components is an essential factor in electrical engineering. Every electronic device produces a certain amount of heat during its operation. This heat can cause overheating and a device can suffer damage. Therefore, the issue of cooling plays a significant role and is an important theme appropriate for continuously finding new improvements.The paper describes a quantification of the heat transfer coefficients between a body and a surrounding environment. Experimental research of the heat transfer by cooling is focused on the plane smooth and structured surfaces. Surface structures improving the heat transfer rate are of dimples. The cooling process was measured by using a thermal imaging camera to obtain a cooling curve – the change in temperature time course during air cooling. The analysis of the cooling curve gradient allows us to identify convective and radiant components of the heat transfer. The presented results in the form of diagrams include different cases of air flow around smooth and dimpled surfaces.

Effect of Laser Surface Texturing on the Tribological Properties and Scuffing Mechanism of CKS Piston Ring Against Cast Iron Cylinder Liner Under High Intensifying

The objective of this study is to characterize and understand the evolutionary processes that the effect of surface texture has on the tribology properties of the Chrom-Keramik-Schicht (CKS) piston ring/cast iron cylinder liner system under high intensifying. Surface dimple textures with an area density of 3–9% were prepared on the CKS piston ring by YAG laser, and the antifriction and antiscuffing properties were tested on a reciprocating test rig at 200 °C and 80 MPa. The minimum friction coefficient and wear loss were both obtained at the area density of 5%, compared with the untextured cylinder liner–piston ring (CLPR). The friction coefficient decreased by 0.013 to 0.086, and the wear loss for the piston ring and cylinder liner decreased by 41% and 46%, respectively. The sharp decrease of the friction force induced by surface polishing of the cylinder liner is taken as a sign to indicate the cylinder scuffing under starved lubrication. The scuffing time for the piston ring/cylinder liner system reached a maximum value of 18 min at an area density of 3%, which is extended about 41% compared with that of the untextured piston ring. The dimple surface texture on the piston ring could extend the scuffing time by delaying the occurrence of polishing behavior on the surface of cylinder liner. It is found that the retarded surface polishing played a major role for the modification of the antiscuffing property of the friction pairs according to the friction curves and wear morphologies.

Numerical Analysis of the Damage Evolution of DP600 Steel Using Gurson–Tvergaard–Needleman Model

This research models the ductile fracture in DP600 steel sheets by using Gurson–Tvergaard–Needleman (GTN) damage model with experimentally obtained parameters. Uniaxial tensile tests are carried out to determine the deformation behavior of the material and obtain GTN model parameters. Further, SEM investigations on the fractured surface of the material display a dimpled surface, which indicates ductile fracture. Also, density measurements are carried out to define the critical and final volume fractions. A finite element model (FEM) of the tensile testing is developed. Then, the experimental parameters of the GTN model are verified by comparing load–displacement curves and porosity values for different zones. The results put forth that the experimental parameters can be used to model the deformation behavior of the DP 600 steel. Further, the growth of total void volume fraction increases exponentially, attributed to the increasing value of stress triaxiality. Also, the shift in the void volume fraction after the critical void volume fraction is explained with the void coalescence. Finally, the thickness of the sheet has a power‐law relationship and the porosity level of the material can be predicted for a known thickness value.

A novel heat sink for cooling photovoltaic systems using convex/concave dimples and multiple PCMs

• PV system integrated with convex/concave dimples and multiple PCMs is numerically studied. • The dimpled surface enhances the melting rate without changing the PCM mass. • The multiple PCMs improve the thermal and electrical performance of the PV system. • The highest performance occurs at (two-PCMs:15–5 mm) arrangement with 8 dimples. The operating temperature of a solar panel affects its electrical efficiency. As the temperature increases, the solar cell's ability to generate electricity decreases so cooling is required to improve its performance. In this study, a novel design of photovoltaic phase change materials (PV-PCMs) system is established. It consists of a separate convex/concave dimpled aluminum plate and multiple PCMs that act as a heat sink. In order to achieve longer thermal management of PVs, the PCMs were arranged along the heat flow direction according to the melting temperatures. The thermal and electrical performance of the PV-PCMs system was numerically analyzed at different inclination angles. The system was tested using different numbers of dimples (smooth, 6, 8, and 10 dimples) and multiple PCMs with different thicknesses (single PCM, two-PCMs:10–10 mm, two-PCMs:15–5 mm) to obtain the optimal design. The numerical model and the literature data agreed very well. The (two-PCMs:15–5 mm) arrangement with 8 dimples provides the longest uniform operating temperature duration and the highest PV electrical efficiency. The thermal management durations were 40, 30, and 25 min, during which the percentage decrease in PV cell temperature was 7.14, 4.65, and 2.22 % at an inclination angle of 90°, 60°, and 30°, respectively, compared to the smooth wall with a single PCM. The novel design is recommended for future modeling of the PV-PCMs system.

Heat gain in an internally dimpled tube heat exchanger - a numerical investigation

Many researchers have looked at heat transfer improvement methods utilizing circular dimpled pipes, surfaces, and other methods in the past. The size and position of dimples, for example, have a major influence on the pipe's flow and thermal properties. Five internally dimpled pipe configurations were analyzed in this computational research. The flow was simulated using ANSYS Fluent 16, with water as the working fluid and steel pipes with internal dimples. The effect of dimple number and diameter on flow and thermal parameters was studied with the five different internal dimple configurations and compared them with plain tube heat exchanger thermal performance under similar conditions. Internal dimples (inside protrusions in tube heat exchanger) resulted in a larger pressure drop in the path of flow from entry to exit. It was discovered that dimples increased the pipe heat exchanger's heat transfer coefficient when compared to the plain tube heat exchanger. A higher pressure loss than plain pipe heat exchangers (HE) was found although the thermal performance was more than that for a plain pipe. The Reynolds number of flows was changed as a result of the pressure drop. When the Reynolds number was lower, the friction factor was found to be higher, resulting in increased heat exchange in the experiment. The results of the numerical analysis for the tube HE with dimples indicate that dimples help mixing of flow in the tube HE and a growth of thermal boundary layer which enhance heat between the hot fluid and cold fluid through the tube HE wall.

Fracture toughness of High-Manganese steels with TWIP/TRIP effects

Three high-manganese steels with different carbon contents were investigated in this work, aiming to explore their elastoplastic fracture toughness, fracture micro-mechanisms and microstructural features. J-R curves were obtained according to ASTM E1820-20 by testing C(T) specimens, applying the unloading compliance method to measure crack extension. The TWIP effect (mechanical twinning + dislocation gliding) developed in Steel A and Steel B with carbon contents of 0.84 wt% and 0.54 wt% respectively. On the other hand, Steel C (carbon content of 0.28 wt%), showed strain-induced γFCC → εHCP transformation associated with the TRIP effect. The three steels presented smooth load (P) vs load-line displacement (v) records; i.e., no instability was observed, which allowed the characterization of fracture toughness by means of J-R curves. Fully dimpled fracture surfaces were observed in Steel A and Steel B, whilst Steel C showed small cleavage facets in some sectors that had not indication in the P vs v records. Best performance in terms of fracture behavior was obtained in Steel B and the poorest in Steel C. In addition to the above, the microstructural analysis of the stable crack growth zones in the fractured specimens allowed the identification of several characteristics.

Tailoring the microstructure to enhance the cryogenic mechanical properties of a Fe–34.5Mn–0.04C steel

Samples of a Fe–34.5Mn–0.04C (wt. %) austenitic steel with average grain size in the range from 0.45 to 21.0 μm were produced by cold rolling and subsequent annealing. The effects of microstructure on room–temperature (RT) and cryogenic tensile properties, and on the related fracture modes, were investigated. It is found that for fully recrystallized samples (those with average grain size in the range from 2.3 to 21 μm), both the yield strength and uniform elongation increase with decreasing grain size at both RT and −180 °C, while for smaller grain sizes (corresponding to partly recrystallized samples) the strength increases at the expense of uniform elongation. In general, samples with an average grain size of 2.3 μm show a better combination of strength and ductility than samples with larger grain sizes. A detailed characterization of the microstructure and fracture surfaces after failure reveals that grain refinement results in elimination of grain boundary martensite, thereby leading to a transition from transgranular and intergranular fracture modes to a ductile fracture mode, characterized by dimpled fracture surfaces. The results are discussed with respect to stacking fault energy and to the Mn and C content. The study provides important inputs for the design of advanced Fe–Mn–C steels for cryogenic applications.

New Directions in Modeling and Computational Methods for Complex Mechanical Dynamical Systems

This paper presents a new conceptualization of complex nonlinear mechanical systems and develops new and novel computational methods for determining their response to given applied forces and torques. The new conceptualization uses the idea of including particles of zero mass to describe the dynamics of such systems. This leads to simplifications in the development of their equations of motion and engenders a straightforward new computational approach to simulate their behavior. The purpose of the paper is to develop a new analytical and computational methodology to handle complex systems and to illustrate it through the study of an old unsolved problem in classical mechanics, that of a non-uniform rigid spherical shell rolling, without slipping, under gravity on an arbitrary dimpled bowl-shaped rigid surface. The new conceptualization provides the explicit equations of motion for the system, the analytical determination of the reaction forces supplied by the surface, and a straightforward computational approach to simulate the dynamics. Detailed analytical and numerical results are provided. The computations illustrate the complexity of the dynamical behavior of the system and its high sensitivity to the initial orientation of the shell and to the presence of any initial angular velocity normal to the surface.