Star-CCM Research Articles

Investigation on the Aerodynamic Parameters of the Triangle Shape of Tall Buildings by Using of CFD Method

Wind loading in large buildings has always been a major challenge for civilian engineers. For this purpose, presenting the optimum exterior forms of a building exposed to the wind flow and analyzing aerodynamic forces, including resistance force, bending, and twisting moments, are challenging issues for designers. Nowadays, by combining various numerical calculation methods, like neural networks, genetic algorithms, and other methods, by changing some parameters, they optimize the external form of the building based on aerodynamic parameters. In this research, three optimized triangular models will be investigated using the computational fluid dynamics method. For wind flow, a velocity profile is used in the three simulations, and Reynolds’ Navier–Stokes average equations are used to solve momentum relationships. Additionally, the κ-ε method was used to calculate Reynolds stresses. The results show that the optimized N3 model is in the most optimal condition possible in terms of aerodynamic parameters such as drag, torsion moment, and vortices behind the building. Nowadays, the neural network algorithm is one of the most famous numerical methods for optimizing hull shapes. However, this approach cannot improve aerodynamic parameters either. Hence, computational fluid dynamics is used to deeply analyze. This research is one step forward to assess the optimized hull shapes of tall buildings. All tests are conducted using STAR CCM+.

Comparative Investigation of Resistance Prediction for Surface Combatant Ship Model using CFD Modeling

The Multi-Mission Surface Combatant (MMSC) is a highly maneuverable combatant ship capable of littoral and open ocean operations. It was designed to confront modern maritime and economic security threats. The MMSC takes the proven capabilities of the littoral combat ship and the inherent flexibility of the Freedom-variant hull to meet the unique maritime requirements of international navies. Computational fluid dynamics (CFD) is applied to present a method to predict the resistance for new surface combatant ship. First, calculations for a typical benchmark DTMB 5415-24 model are carried out using three different mesh sizes for Froude numbers from 0.10 to 0.48 for the purpose of model validation by Star CCM+. The numerical results are compared with the experimental data and the published CFD solutions in terms of wave field and resistance coefficients for accuracy of the solution parameters. Finally, the method is used to study the influence of Froude number variation on the total resistance and wave pattern for the new combatant ship model under the same conditions. Quantitative agreement between the numerical simulations has been observed. This demonstrates that our CFD model is capable of simulating the steady flow around a ship hull with an acceptable accuracy and thus can be used as a complementary tool to laboratory model tests for ship design and ship hydrodynamic research.

Influence of Longitudinal Wind on Hydrogen Leakage and Hydrogen Concentration Sensor Layout of Fuel Cell Vehicles

Hydrogen has the physical and chemical characteristics of being flammable, explosive and prone to leakage, and its safety is the main issue faced by the promotion of hydrogen as an energy source. The most common scene in vehicle application is the longitudinal wind generated by driving, and the original position of hydrogen concentration sensors (HCSs) did not consider the influence of longitudinal wind on the hydrogen leakage trajectory. In this paper, the computational fluid dynamics (CFD) software STAR CCM 2021.1 is used to simulate the hydrogen leakage and diffusion trajectories of fuel cell vehicles (FCVs) at five different leakage locations the longitudinal wind speeds of 0 km/h, 37.18 km/h and 114 km/h, and it is concluded that longitudinal wind prolongs the diffusion time of hydrogen to the headspace and reduces the coverage area of hydrogen in the headspace with a decrease of 81.35%. In order to achieve a good detection effect of fuel cell vehicles within the longitudinal wind scene, based on the simulated hydrogen concentration–time matrix, the scene clustering method based on vector similarity evaluation was used to reduce the leakage scene set by 33%. Then, the layout position of HCSs was optimized according to the proposed multi-scene full coverage response time minimization model, and the response time was reduced from 5 s to 1 s.

Performance investigation of hybrid photovoltaic thermal-heat with mini-channels for application in electric vehicles

The first autonomous car was developed in the 1980s, but it wasn't until the early 2010s that the technology began to gain significant attention and investment. In 2010, Google began testing self-driving cars on public roads, and since then, many other companies have joined the race to develop fully autonomous vehicles. Hybrid PVT (Photovoltaic Thermal) heat exchangers cooled with mini-channels find application in autonomous vehicles as a solution that enables efficient cooling of the vehicle's electronics and batteries. The solution involves using photovoltaic panels to generate electricity and removing the heat produced during the process using mini-channels is removed by mini-channels. Hybrid PVT heat exchangers cooled with mini-channels can help maintain appropriate temperatures inside autonomous vehicles that generate large amounts of heat from electronic systems and sensors. The setup can improve the performance and reliability of autonomous systems, increase energy efficiency, and reduce energy demands. The experimental setup includes two parallel mini-channel systems separated by a smooth copper plate. The study aims to determine local heat-transfer coefficients, with a cooled solar cell efficiency range of 10% to 14% compared to other research. The cooled PV temperature range achieved was from 19.6 to 22.4 degrees Celsius, which is favorable for photovoltaic panels' operation under approximate light intensity for Poland's latitude. Heat-transfer from hot surfaces to cold fluids is analyzed during single-phase convection using two calculation methods: one-dimensional and numerical simulations using Simcenter STAR CCM+. Cooling photovoltaic modules is critical for the photovoltaic and autonomous vehicle systems sector, making this research significant both theoretically and practically. The research and methods presented in the article on mini-channel cooling of photovoltaic systems and autonomous vehicle systems are innovative at a global scale, and are crucial for further development of sustainable energy systems and reduction of greenhouse gas emissions.

A Mesh Convergence Study on 2-D Air Bubble Barrier Simulation with Mean of Inlet Static Pressure and Horizontal Surface Velocity

Timing is vital for oil spill response operations. However, deployment of the traditional response equipment, unfortunately, takes much more time. Therefore, innovative solutions are needed to minimize time losses. One of these innovative solutions is the air bubble barrier. Air bubble barrier creates a barrier to anything floating in the water, especially keeping the floating oil and petroleum in the area where it is spilled. Computational Fluid Dynamics simulation has grown in importance as a resource for air bubble barrier studies in recent years. Despite the extraordinary success of Reynolds Averaged Navier-Stoke applications on air bubble barriers, just a few studies concentrate on mesh sensitivity, one of the most fundamental issues with CFD methods. The main purpose of this study is to perform a mesh convergence study by simulating an air bubble barrier in the Simcenter STAR CCM+ software. In this context, in this simulation, a 2D numerical model is considered. The mesh convergence study has been performed by calculating the aperture inlet mean static pressure and the mean horizontal surface velocity. As a result, it is evident that the mesh base size and number of elements in mesh in case 10 can be employed to maintain the solution time-optimal state in the upcoming numerical simulations on the 2D and 3D air bubble barrier. Case 10 represents the mesh base size of 0.015 and the number of elements in mesh of 99042. Findings from this parametric study will be incorporated as mesh control rules into the subsequent 2D and 3D simulations of the air bubble barrier.

3D Thermal Simulation of Thermal Runaway Propagation in Lithium-Ion Battery Cell Stack: Review and Comparison of Modeling Approaches

Three empirical modeling approaches for the heat release during a lithium-ion battery cell thermal runaway (TR) are analyzed and compared with regard to their suitability for TR propagation simulation. Therefore, the experimental results of a battery cell stack experiment consisting of five prismatic lithium-ion batteries (>60 Ah) are compared to simulation results of a model that is built within the 3D-CFD framework of Simcenter Star-CCM+®. In contrast to previous studies, the proposed model takes into account detailed phenomena such as the formation of a gas layer between jelly roll and cell can due to electrolyte vaporization, which is crucial to reproduce experimental results. Only two of the three modeling approaches are suitable for TR propagation simulation of the cell stack experiment investigated in this study. These approaches either use time-dependent or spatially resolved temperature-dependent heat release rates. The proposed consideration of gas layer formation as well as the comparative analysis of the modeling approaches contribute to the improvement of TR propagation simulations and support engineers as well as researches to design a safer battery pack.

NUMERICAL SIMULATION OF THE PROCESS OF AERODYNAMIC SEPARATION OF FINE-GRAINED BULK MATERIAL

Various methods can be used to numerically simulate the aerodynamic separation of fine-grained bulk material, including discrete element methods, finite element methods, and bounded domain methods. In all these methods, these equations are solved numerically, and the results are used to determine the trajectories and velocities of air and particles. The Discrete Element Method (DEM), on the basis of which the study will be conducted, is designed for modeling the granular flow of materials. The purpose of the research is to simulate the movement of fine-grained loose material under the influence of air flow and calculate the parameters of its aerodynamic separation in the Simcenter STAR-CCM+ software package. The following were selected as physical models: gas, two-dimensional, separated flow, gradients, ideal gas, isothermal fluid energy equation, unsteady implicit, turbulent, Reynolds averaging of the Navier-Stokes equation, K-Epsilon turbulence model, admissible two-layer K-Epsilon, wall distance, double layer for any y+, gravity, Lagrangian multiphase, DEM discrete element model, multiphase interaction. As a result of the numerical simulation of the movement of fine-grained loose material under the influence of the air flow in the Simcenter STAR-CCM+ software package, the distribution of their components in the area of the separator was constructed. The following parameters were adopted as research factors: the diameter of the particles of the liquid fraction and impurities d, the particle supply speed f, the air flow speed v. Based on the results of the processing of the obtained data set in the Wolfram Cloud software package, the patterns of changes in the position of the intersection line of the distribution of two fractions (distance x) and the content of impurities δ in the liquid zone of separation from research factors were established. The presented detailed method of numerical modeling can be used to study other methods of separation of fine-grained loose materials.

대형 비행갑판을 갖는 함정과 풍동시험 결과를 활용한 고신뢰도 함정 Airwake 예측

Developing high-fidelity Computational Fluid Dynamics (CFD) simulation methods used to evaluate the airwake characteristics along a flight deck of a large ship, the various kind of data such as actual ship measurement and wind tunnel results are required to verify the accuracy of CFD simulation. Inflow velocity profile at the bow, local unsteady flow field data around the flight deck, and highly reliable wind tunnel data which were measured after reviewing Atmospheric Boundary Layer (ABL) simulation and Reynolds Number effects were also used to determine the key parameters such as turbulence model, time resolution and accuracy, grid resolution and type, inflow condition, domain size, simulation length, and so on in STAR CCM+. Velocity ratio and turbulent intensity difference between Full-scale CFD and actual ship measurement at the measurement points show less than 2% and 1.7% respectively. And differences in velocity ratio and turbulence intensity between wind tunnel test and small-scale CFD are both less than 2.2%. Based upon this fact, the selected parameters in CFD simulation are highly reliable for a specific wind condition.

AI based temperature reduction effect model of fog cooling for human thermal comfort: Climate adaptation technology

This study developed a gradient-boosted regression tree-based artificial intelligence (AI) model––temperature reduction effect AI model (TREAM)––to determine the temperature reduction effect of fog cooling that varies with weather conditions. According to the trend of global warming, our society is suffering from serious damage from urban heat islands, especially negatively affecting human health and thermal comfort. Therefore, it is very important to develop and evaluate adaptive technology for providing pleasant thermal comfort to humans. This study select fog cooling as adaptive technology for human thermal comfort, and indoor and outdoor simulation were performed using STAR CCM+, a computational fluid dynamics(CFD) program. Moreover, transient analysis to validate the outdoor model of CFD and parametric study to identify the correlation between the environmental factors and fog cooling were performed. When initial temperature set as 45 °C at a relative humidity of 90% and wind speed of 1 m/s, a temperature reduction of 8.92% can be obtained. Regardless of the temperature and humidity conditions, the temperature reduction effect of fog cooling was ∼1% if the wind speed increased above 5 m/s. This study contributed to the quantitative analysis of the temperature reduction effect according to the change of environmental factors.

CFD modeling of vertical-axis wind turbine wake interaction

Since wind turbines placed in wind farms need to minimize their footprint on the ground, the effects of the wake must be considered. Placement optimization, turbine spacing, and direction of rotation are known to affect the performance of vertical-axis wind turbines (VAWTs). However, rigorous numerical modeling methodologies that investigate the influence of these characteristics are lacking, especially in the case of large wind turbines. The goal of this study is to analyze turbine configurations that might enhance the power production of VAWT farms using two-dimensional CFD models based on the Star CCM+ package. The novelty of this work is to analyze wind farm configurations for very large turbines. This is important because large turbines are much more performant than small turbines and have a high power coefficient. Results show that CFD simulations adequately capture the performance of wind turbines in farms with multiple VAWTs. In general, if a second rotor is spaced more than 10 turbine diameters downstream of the first rotor, the effect of the wake is less significant. Furthermore, a specific farm configuration with five VAWTs is investigated and shows a 20% increase in power output compared with the same number of turbines operating in isolation.

A multi-time scales semi-decoupled CHT (Coupled Heat Transfer) model and its application on piston transient heat transfer simulation

Transient CHT simulations between in-cylinder combustion and chamber components are difficult to achieve due to time scale issues. In this study, a multi-time scales semi-decoupled CHT model is proposed and verified by mature CFD (Computational Fluid Dynamics) tools (e.g., Openfoam, Star CCM+, and Fluent) in a simple structure. Then, the established model is used to simulate the transient CHT process between the in-cylinder combustion and the piston. The calculated results are compared with the experimental results of the piston hardness plug. The 1D (one Dimensional) analysis demonstrates that the amplitude of the solid temperature fluctuation reaches an equilibrium state almost at the beginning of the calculation. The comparative results show that the calculation speed of the multi-time scales semi-decoupled CHT model is increased by about 15 to 20 times. The accuracy of the calculated results of the four methods is highly consistent (the difference is less than 0.4 °C). In the coupled heat transfer simulation of the piston and in-cylinder combustion, only four in-cylinder cycles are calculated to achieve the convergence of piston temperature. The hardness plug test value on the piston's top surface is higher than the peak value of the temperature wave.

Seakeeping analysis of a tanker with hard sail-based wind propulsion system in various seaways

A hard sail is a type of wind-assisted ship propulsion (WASP) technology that incorporates wind energy to propel the ship with the help of sails and can significantly reduce the ship's energy consumption. This study focuses on the seakeeping analysis of a hard sail-assisted KVLCC2 ship in different wave conditions. A numerical simulation of the aerodynamic performance of a sail system consisting of two sails was done on ANSYS Fluent and compared with corresponding experimental data. The motion response and added resistance of a KVLCC2 hull in regular waves were numerically predicted in STAR CCM + software and compared with corresponding seakeeping experimental test data. The numerical results obtained for the tanker in regular waves show reasonable accuracy in predicting the hydrodynamic responses of the ship as compared to experimental data. A static analysis was conducted in MAXSURF software to verify the stability of the full-scale ship after the installation of the hard sails. Finally, computational analysis was carried out for the sail-installed KVLCC2 hull to evaluate its hydrodynamic performance for different wave conditions like the regular and irregular head sea as well as beam sea conditions along with expected operational and severe wind speeds corresponding to the model scale hull. The results show that the added resistance and motion amplitudes for the sail-assisted KVLCC2 ship do not change significantly in both operational and severe head sea conditions. However, in the case of a beam sea, there is a significant increase in both added resistance and motion amplitudes.

Numerical Analysis of the Effect of the Vortex Finder on the Hydrocyclone’s Split Water Ratio and Separation Performance

Hydrocyclones are devices used in numerous areas of the chemical, food, and mineral industries to separate fine particles. A hydrocyclone with a diameter of d50 mm was modeled using the commercial Simcenter STAR-CCM+13 computational fluid dynamics (CFD) simulation package. The numerical methods confirmed the results of the different parameters, such as the properties of the volume fraction, based on CFD simulations. Reynolds Stress Model (RSM) and the combined technique of volume of fluid (VOF) and discrete element model (DEM) for water and air models were selected to evaluate semi-implicit pressure-linked equations and combine the momentum with continuity laws to obtain derivatives of the pressure. The targeted particle sizes were in a range of 8–100 microns for a dewatering application. The depth of the vortex finder was varied to 20 mm, 30 mm, and 35 mm to observe the effects of pressure drop and separation efficiency. The split water ratio increased toward a 50% split of overflow and underflow rates as the length of the vortex finder increased. It results in better particle separation when there is a high injection rate at the inlet. The tangential and axial velocities increased as the vortex finder length increased. As the depth of the vortex finder length increased, the time for particle re-entrainment into the underflow stream increased, and the separation efficiency improved.

Numerical analysis of the dynamic behavior of a Floating Wind Platform in regular waves

The goal of this study is to analyze the hydrodynamic behavior of a Floating Wind Platform (FOWT) under regular wave conditions. The analysis considers three degrees of freedom: Heave, Pitch and Surge. The study was car-ried out using a CFD (Computational Fluid Dynamics) tool, based on the Navier-Stokes equations and the Finite Volume Method, and results were compared against experimental tests performed at the Wave/Towing Tank at Universidad Austral de Chile (CEH-UACh). For this analysis, a generic scales semi-submersible platform was used under different regular wave conditions, obtain-ing wave height data at different points of the control volume and translation and rotation movements to obtain the RAO's (Response Amplitude Operator) in each of the considered degrees of freedom. For the CFD simulations, commercial software STAR CCM+ was used, where the flow characteristics were defined through Volume of Fluid (VOF) and their respective boundary conditions. Final-ly, the results of both methodologies were compared, showing an adequate de-gree of correlation between them.

Simulation of the process of interaction of the working bodies of tillage machines with the soil in Simcenter STAR-CCM+

To study the process of interaction between the working bodies of soil tillage machines and the soil, it is necessary to create a physical and mathematical model of the environment that reflects the physical and mechanical properties of the real soil as accurately as possible. The existing analytical models are used separately from each other, which leads only to a one-sided consideration of the scientific and technical problem. Today, it is quite difficult for agricultural engineers to investigate the process of interaction of tillage working bodies with the soil during the design of new structures due to the lack of simple analytical physical and mathematical models. In order to simplify these calculations within the framework of agricultural machinery engineering, it is necessary to use software that will combine the achievements of agricultural mechanics. The goal is to simulate and study the process of interaction of tillage working bodies with the soil using Simcenter STAR-CCM+. In the course of the study, the interaction process of the most common tillage working bodies, such as a cultivator’s arrow foot, a disc harrow on an elastic rack, a deep loosener (chisel plow), a flail plow and a smooth roller, was simulated using volume of fluid (VOF) and discrete element methods. (DEM). The application of the VOF method allows to determine the non-primary flow of the soil relative to the working body, and the DEM method allows to determine the distribution of velocities and interaction forces of soil particles. With the help of Simcenter STAR-CCM+, it is possible to visualize the interaction process and determine the height of the ridges formed and the depth of the furrows and their location in space

Development and characterization of a low-NOx partially premixed hydrogen burner using numerical simulation and flame diagnostics

The utilization of hydrogen as a fuel in free jet burners faces particular challenges due to its special combustion properties. The high laminar and turbulent flame velocities may lead to issues in flame stability and operational safety in premixed and partially premixed burners. Additionally, a high adiabatic combustion temperature favors the formation of thermal nitric oxides (NO). This study presents the development and optimization of a partially premixed hydrogen burner with low emissions of nitric oxides. The single-nozzle burner features a very short premixing duct and a simple geometric design. In a first development step, the design of the burner is optimized by numerical investigation (Star CCM+) of mixture formation, which is improved by geometric changes of the nozzle. The impact of geometric optimization and of humidification of the combustion air on NOx emissions is then investigated experimentally. The hydrogen flame is detected with an infrared camera to evaluate the flame stability for different burner configurations. The improved mixture formation by geometric optimization avoids temperature peaks and leads to a noticeable reduction in NOx emissions for equivalence ratios below 0.85. The experimental investigations also show that NOx emissions decrease with increasing relative humidity of combustion air. This single-nozzle forms the basis for multi-nozzle burners, where the desired output power can flexibly be adjusted by the number of single nozzles.

Computational fluid dynamics approach to study methane hydrate formation in stirred reactor

Hydrate formation management in oil and gas industries needs a detailed understanding of hydrate formation phenomena in terms of dynamics and kinetics aspects. Stirred reactors are one of the popular experimental systems to study hydrate formation/dissociation in terms of kinetics and thermodynamics mechanisms. Various processes/systems such as gas hydrate formation and decomposition phenomena in oil and gas facilities are simulated using computational fluid dynamics (CFD). This research examines the hydrate formation in a stirred reactor for a water-methane system using the Eulerian multiphase flow model by employing CFD software (STAR CCM +). The developed numerical model incorporates the conservation equations of momentum, mass, and energy, where the hydrate equations, including mass transfer, hydrate kinetics, and heat of hydrate formation, are included in the governing equations. In this paper, the methane hydrate formation in the stirred reactor for the stirring rate of 300 RPM and volume fraction of 0.04 with a pressure of 5,500 kPa is simulated. Then, the simulation results are validated using the experimental data collected from the literature, resulting in an overall absolute average deviation percentage (AAD%) of 15.6 %. The influences of stirring rate (300 to 500 RPM), methane volume fraction (0.04 to 0.4), pressure (3,500 to 7,500 kPa), and subcooling (1.96 to 9.23 °C) are studied on the hydrate formation in the agitated reactor. The results reveal that the developed CFD model can predict the methane hydrate formation in the stirred reactor with acceptable precision. According to the simulation runs, methane hydrate is formed mainly near the walls and around the stirrer blades. In addition, an increase in subcooling, gas volume fraction, pressure, and stirring rate leads to more hydrate formation in the reactor with a constant temperature of 274.3 K. The maximum mass fraction of hydrate is observed for the case when the gas volume fraction and stirring rates are 0.4 and 900 RPM, respectively. However, the minimum value of methane hydrate is 0.092 g, where the volume fraction and impeller speed are 0.04 and 300 RPM.The findings of this study can help to further understand hydrate formation phenomena in oil and gas facilities. This model can provide oil and gas engineering sectors with effective strategies to control and manage gas hydrates. In addition, the proposed CFD model can be helpful for engineers and researchers in the petroleum industry to simulate hydrate formation in other complicated geometries in petroleum facilities.

Чисельне моделювання пружного гістерезису сипкого матеріалу

The elastic hysteresis of bulk material is an important problem in many fields of science and technology, including mining and metallurgy, construction, energy, and engineering. This is due to the fact that loose materials consist of a large number of particles that can shift relative to each other under the influence of external loads. This process is accompanied by energy losses and changes in the shape of the material structure, which in turn leads to elastic hysteresis. Knowledge of material behavior under various loading conditions is essential for developing safe and effective engineering solutions. The purpose of the research is to determine the parameters of the deformation of loose material (for example, granular material) depending on its physical and mechanical properties in the Simcenter STAR-CCM+ software package. The elastic hysteresis loop reflects the behavior of the material under cyclic loading, when strain and stress changes occur. Loop area is a measure of material energy losses that occur during cyclic loading. As a result of numerical modeling of the process of deformation of loose material (on the example of granular material), the regression equations of the second order of the dependences of the area of the elastic hysteresis loop and the maximum force value at 25% relative deformation of the granular material from its physical and mechanical properties (density, Poisson's ratio and Young's modulus) were obtained. The presented results can be used in further modeling or in the creation of physico-mathematical models of the process of compression of grain material in granulators, extruders and expanders.

THE WATER FLOW MOVEMENT MODELING IN PASSIVE DISINTEGRATOR OF THE GRAIN MOLASSES’ INSTALLATION

The equipment features’ studying is important because the volume of small and medium sized businesses related to dairy and meat farming in our country is growing. It is also important for the energysaving technologies’ developing and improving. Due to the grain’s high demand as a farm animals’ feed element, its processing technologies are being developed and widely used. In particular, technologies and technical means of grain molasses preparing have been developed. The scheme of grain molasses preparation and modeling conditions are given, water movement in a passive shredder’s modeling results are presented. This modeling in the Star CCM+ program was carried out. The water flow around two grids located at a distance equal to 100 and 200 mm was set; the pipe diameter d = is 30 mm, calculated section length - 1 m. At looking through the fields’ velocity and fluid flow’s lines in the shredder, it was revealed that the flow rates in both cases under consideration are almost identical. There is a velocity clear increasing when the liquid passes through the openings of the gratings and the water bends around the gratings up to a value of 23 m/s. The gratings’ presence in the shredder leads to network resistance and flow power loss’s increasing. The distance between the grids increasing allows to reduce slightly the resistance of the network (in 3%) and flow power’s loss (in 5%). The fluid motion’s given modeling has shown that the passive shredder scheme in the form of a circular tube with two grids installed in it can be considered ineffective due to the proposed device’s high resistances.

Applying multiphysics simulation features of Simcenter STAR-CCM+ for semiconductor manufacturing processes

Applying multiphysics simulation features of Simcenter STAR-CCM+ for semiconductor manufacturing processes