Computational Fluid Simulation Research Articles

Development of a Multi‐Scale Meteorological Large‐Eddy Simulation Model for Urban Thermal Environmental Studies: The “City‐LES” Model Version 2.0

AbstractTo bridge the gaps between meteorological large‐eddy simulation (LES) models and computational fluid dynamics (CFD) models for microscale urban climate simulations, the present study has developed a meteorological LES model for urban areas. This model simulates urban climates across both mesoscale (city scale) and microscale (city‐block scale). The paper offers an overview of this LES model, which distinguishes itself from standard numerical weather prediction models by resolving buildings and trees at the microscale simulations. It also differs from standard CFD models by accounting for atmospheric stratification and physical processes. Noteworthy features of this model include: (a) the calculation of long‐ and short‐wave radiations in three dimensions, incorporating multiple reflections within urban canopy layers using the radiosity method, and accounting for building and tree shadows in the simulations; (b) the provision of various heat stress indices (Universal Thermal Climate Index, Wet Bulb Globe Temperature, MRT, THI); (c) the assessment of the efficacy of heat stress mitigation measures such as dry‐mist spraying, roadside trees, cool pavements, and green/cool roofs strategies; (d) the capability to run on supercomputers, with the code parallelized in a three‐dimensional manner, and the model can also run on a graphics processing unit cluster. Following the introduction of this model, the study confirms its basic performance through various numerical experiments, including simulations of thermals in the convective boundary layer, coherent structure of turbulence over urban canopy, and thermal environment and heat stress indices in urban districts. The model developed in this study is intended to serve as a community tool for addressing both fundamental and applied studies in urban climatology.

Downdraft Gasifier for Oil Palm Empty Bunches with Computational Fluid Dynamics

Abstract The demand for palm oil increases every year and this condition proportional to the increase in waste from the manufacture of palm oil. Therefore, this study aims to determine the potential of empty palm fruit bunches to be used as renewable energy. This research simulated Computational Fluid Dynamic (CFD) gasification with empty oil palm fruit bunches using a downdraft gasifier, then simulated with three variations of air flow rates. This is done because the air flow rate is very influential on the temperature and gasification results. The best and uniform variation was obtained at a water flow rate of 25 L/min with a resulting temperature of 28 °C to 957 °C and with an even temperature coverage in the reactor. Then in this study the syngas H2, CO, CO2 and CH4 were obtained which were not evenly distributed in the reactor at all variations of air flow rate, and for the acquisition of syngas H2, CO, CO2 and CH4 the most were obtained at variations of air flow rate of 25 L/min.

Aerodynamic and Structural Design Procedures Supported by Fabrication and Flight Testing of a Small Unmanned Helicopter

In this work, typical design, production, and testing procedures for a small unmanned helicopter are explained and performed. In doing so, preliminary sizing of the helicopter and three main disciplines are conducted: aerodynamic analytical and numerical simulations, power calculations, and structure analysis assessment. First, a thorough survey is implemented to obtain the trends for the maximum take-off weight versus some design constraints such as rotor diameter, motor power, payload, and empty weight. Performance calculation results are obtained to figure out all aspects that correspond to the specified mission. The designed rotor geometry along with the aerodynamic characteristics and flight performance variables is then validated using the blade element theory and numerical simulations. Second, based on the power curves obtained for different flight regimes, an electric brushless motor is selected. The numerical simulations (Computational Fluid Dynamics) analysis is used to enhance the selection which implies that the motor power should be greater than 5.4 kW to overcome the drag forces. The motor power selection corresponds to a maximum rotor pitch angle of 15∘ and a maximum rotor speed of 1450 RPM. Then, the aerodynamic loads are used as an input for the structural analysis using one-way coupling of fluid–structure interaction (FSI) and consequently designing the internal structure of the blade. Eventually, the internal structure manufactured using carbon fiber-reinforced polymer (CFRP) by applying a combined technique between wet layup and compression molding. The blade is statically tested compared with numerical finite element model results. The fuselage structure along with hub and tail units is manufactured and assembled with the existing on-shelf components to examine the helicopter lift capability with different payloads up to 9 kg. The results show that the detailed design process is significant for manufacturing such blades and the helicopter is capable of lifting off the ground with various payloads depending on the rotor pitch angles (8∘, 12∘, and 15∘) at a constant rotor speed of 1450 RPM.

Bilateral bidirectional cavopulmonary connection: a review of surgical techniques and clinical implications.

The presence of bilateral superior caval veins (bSCVs) could negatively influence the outcome of Fontan patients. In the setting of a bilateral bidirectional Glenn, the selective blood flow to the ipsilateral long with consequent flow stagnation in the connecting portion could lead to poor growth of the central portion of the pulmonary artery, potentially affecting the eligibility for Fontan completion and being associated with a higher incidence of thrombotic complications. Alternative surgical techniques have been described to perform a bidirectional cavopulmonary anastomosis in the presence of bSCVs aiming to achieve a balanced growth of the pulmonary bifurcation. The short-term results of these techniques such as the V- or Y-shape seem to be excellent; however, some anatomical settings could affect the feasibility of these techniques. The so-called "unifocalization" creates a configuration comparable to a "normal" bidirectional Glenn and could be a feasible alternative. However, the long-term results of this technique are not published yet. The positive effect of additional pulsatile pulmonary flow on pulmonary artery growth should be considered in case of bilateral bidirectional Glenn, despite the higher incidence of postoperative complications reported and the difficult calibration of the amount of additional flow. The role of computational fluid dynamic to simulate the surgical strategy in single ventricle patients is promising and could be worthwhile in the setting of bSCVs. In fact, the surgical techniques of bilateral bidirectional Glenn could be simulated testing their feasibility and allowing to identify the more favorable hemodynamic pattern, patient specific. This review article highlights the critical issues related to the presence of bSCVs in univentricular physiology, analyzing pros and cons of the different surgical techniques. Besides reviewing the literature, this manuscript focuses on the role of computational fluid simulation in identifying the most favorable surgical technique with an individualized approach, which could potentially improve the clinical outcome.

High-resolution CFD modelling of Lillgrund Wind farm

We report on a fully dynamic simulation of Vattenfall’s Lillgrund offshore Wind Farm, with a focus on the wake effects of turbines on the performance of individual turbines, and of the farm as a whole. The model uses a dynamic representation of a wind turbine to simulate interaction between the wind and the turbine rotors, calculating the instantaneous power output and forces on the air; this was embedded in a finite element, large eddy simulation (LES) computational fluid dynamics code. This model was applied to the wind farm for a selection of key wind speeds and directions, to investigate cases where a row of turbines would be fully aligned with the wind or at specific angles to the wind. The simulation results were then compared to actual performance measurements from the wind farm spanning several years’ of operation. These results demonstrate that time-resolving LES simulations are able to reproduce realistic wake structures, including wake meandering and wake recovery, as well as the effect of wakes on turbine performance.

Design optimization of staggered-arranged battery thermal management system using an integrated approach of physics-based simulations and evolutionary algorithms

The widely used Lithium-ion battery cells (LIBs) are very sensitive to the operating temperature, which impacts the cycle life and sometimes even leads to thermal overshoot. Hence, a battery thermal management system (BTMS) is required to maintain the temperature of the batteries within the optimum range and maintain the temperature uniformity among the battery pack. A BTMS can be configured in different architectures and either the air or a liquid can be used as a heat transfer fluid. Finding an optimum architecture configuration of BTMS is challenging which requires an economical solution based on comprehensive numerical parametric investigation and multidisciplinary design optimization. In addition, there are lot of uncertainties in design variables (inputs) which could affect the thermal performance of the battery. Therefore, this work proposes a comprehensive study on the design optimization of staggered-arranged BTMS air cooling system using an integrated approach of physics-based simulation (computational fluid dynamics simulations), parametric optimization using statistical design of experiments and evolutionary algorithms such as genetic algorithm (GA), and particle swarm optimization (PSO). The proposed approach incorporates the findings obtained from physics-based simulations in evolutionary algorithms to guide the solutions to obtain efficient and close-to-realistic solution. The numerical model has been mathematically validated using a variety of empirical heat-transfer correlations, and the outcomes are in good concurrence with one another. The comparative analysis investigation reveals that GA outperformed PSO and the optimization process yielded significant improvements including 0.627 % reduction in maximum temperature, 49.18 % decrease in maximum temperature difference, 102.379 % increase in pressure drop, and 6.804 % increment in volume. Conclusions are made and research recommendations are proposed for the future work.

A wide ranging experimental and kinetic modeling study of TMEDA pyrolysis and oxidation

Traditional liquid propellants like unsymmetrical dimethylhydrazine include several issues, such as toxicity, short storage time and preservation difficulty at low temperatures. For this reason, exploring green and stable propellant fuels is imperative in the development of propellants. Tetramethyl ethylenediamine (TMEDA) is considered to be a promising green propellant fuel with high specific impulse, non-toxicity, and long-term storage stability. Thus, investigating the combustion characteristics of TMEDA and constructing a detailed chemical kinetic mechanism are of fundamental importance in describing its combustion in computational fluid simulation. For this work, ignition delay times of TMEDA were measured in a shock tube at equivalent ratios of 0.5, 1.0 and 2.0, at pressures of 2, 10, and 20 bar, and in the temperature range of 870–1500 K with fixed fuel concentration at 2 %. After the reflected shock at 990–1500 K, the pyrolysis products of 2000 and 5000 ppm TMEDA in Argon were also measured at 5 and 10 bar conditions in a single pulse shock tube. In addition, laminar flame speeds of TMEDA were measured at initial pressures of 1 bar, initial temperatures of 333 and 353 K, and equivalence ratios ranging from 0.8 to 1.5 in a constant volume reactor. The experimental results were simulated using a detailed TMEDA kinetic mechanism. Reaction path analysis and sensitivity analysis were provided to clarify the chemical kinetics of TMEDA oxidation and pyrolysis. The current work provides new experimental data and fundamental analyses for understanding the oxidation and pyrolysis characteristics of TMEDA, and sheds light on optimal directions for future models.

Design of a multi-direction piezoelectric and electromagnetic hybrid energy harvester used for ocean wave energy harvesting

Ocean waves contain a great deal of energy, and the collection and utilization of wave energy is of great significance for sustainable development. In this paper, a multi-direction piezoelectric and electromagnetic hybrid energy harvester (PEHEH) based on magnetic coupling is proposed that can collect low frequency vibration energy from multiple directions. The proposed PEHEH combines piezoelectricity and electromagnetism through magnetic coupling to collect energy in the same excitation. The mechanical model of the PEHEH is established, and finite element simulation software COMSOL and computational fluid dynamics are used to analyze and verify the feasibility and practicability of the PEHEH structure. An experimental platform is built to test the output performance of the PEHEH. The results show that the maximum energy generated by PEHEH is 19.4 mW when the magnetic distance is 16 mm and the excitation frequency is 9 Hz. The hybrid energy harvester can light 56 light emitting diodes, which verified the feasibility of practical application. Therefore, the proposed hybrid energy harvester can effectively collect low-frequency wave energy and has a broad application prospect as a power source for low-power electronic devices.

A numerical methodology for estimating site-specific cascading earthquake and tsunami dynamic loading on critical infrastructure

A numerical methodology for deriving cascading earthquake and tsunami loading patterns for use in critical infrastructure design is proposed. Earthquake source parameters are first used to generate synthetic ground motion acceleration time series at the site of a critical infrastructure using an open-source stochastic extended finite-source simulation algorithm. Using the same earthquake source information, the tsunami phases of generation, propagation, and inundation are modeled using a coupling approach for determining tsunami wave forces. The coupling approach combines (1) a code based on non-linear shallow water equations solved by the Finite Volume method, which is used to capture the tsunami flow characteristics from generation through the inundation phase until relatively close to the structure, coupled with (2) an open-source computational fluid simulation code, which relies on solving the Navier–Stokes equations using the Smoothed Particle Hydrodynamics method. An appendix presents the validation of the numerical methodology through correlation of the numerical simulations with field data recorded during the 2011 Japan Earthquake and Tsunami. The methodology is then employed to characterize the ground shaking and tsunami loading patterns at the site of the container terminal of the Sines deep-water seaport in Portugal, when subjected to the historic 1755 Great Lisbon Earthquake and Tsunami plausible scenarios. For the site, the generated ground motion acceleration time series show peak accelerations exceeding Eurocode 8 design values. Tsunami flow depths and velocities were computed in horizontal and vertical directions and could be used in the assessment of the existing infrastructure or the design of the future expansion of the port.

Eccentric drop of a control rod in the guide tube with annular gap flow

The drop time of control rod is essential for safety analysis of nuclear power plant. The motion of control rod can be characterized by an annular gap flow with large blockage ratio. In this study, we studied the effects of the eccentricity between the control rod and the guide tube on the annular gap flow, and further on the drop time. By considering the added mass and the upward flow of fluid in the annular gap, we developed a theoretical model for computing the drop time of eccentric rod. In the proposed model, particularly, the annular gap flow velocity was obtained from full-scale computational fluid simulations with respect to blockage ratio and eccentricity. The simulation and experiment results agree well on the drop time, the histories of velocity and acceleration, and the hydrodynamic characteristics. Results show that the drop time increases drastically when blockage ratio α increases from 0.83 to 0.91, and the eccentricity effect on drop time is negligible when the blockage ratio is small (e.g., α < 0.83). Nevertheless, for large blockage ratio (α ≥ 0.83), the drop time increases significantly for eccentric rod drop, especially for a lighter control rod. The present study provides a general method for analysis of control rod drop, which is critical for the nuclear reactor design.

Analysis on influence of self-fan cooling motor on fan aerodynamics

With the development of multi electric/all electric aircraft, the degree of aircraft secondary energy electrification is becoming higher and higher. As the core component of the electrical system, the motor presents the trend of small volume and high-power density. The heat dissipation problem of compact motor is becoming more and more serious. At present, the self-driven fan cooling system is widely used in aircraft motors. In this paper, the axial fan cooling system of an aero generator is taken as the research object, and the changes of fan flow field and aerodynamic characteristics in the fan motor coupling model of the isolated fan and the installed motor are analyzed by using three-dimensional computational fluid simulation. At the same time, the influence of the change of the axial distance between the fan and the motor on the aerodynamic performance is also studied. The analysis of the simulation results shows that the close coupling between the motor and the fan components greatly affects the flow structure in the fan, resulting in the distortion potential effect on the fan outlet section. The fan flow field appears the blade root reflux, the channel vortex in the blade and the expansion of the corner separation area. With the increase of the axial distance between the motor and the fan, the influence of the motor on the flow in the fan gradually approaches the flow blocking effect.

Failure analysis of pulverizer pipe elbow in PLTU boiler

Erosion occurs due to several different mechanisms, depending on the composition, size, shape of the eroding particles, speed, angle of impact, and surface composition of the eroded components. The pulverizer pipe elbow has become worn out due to the pulverized coal fluid abrasion flowing on the pipe, which the type is AISI Grade 1026. This study was carried out on the causes of this damage case. Damage to the elbow in the boiler needs to be analyzed for the failure of the elbow so that the damage's cause is known and it becomes a lesson so that the same damage does not occur again. The research aims to: 1. Find out the cause of damage to the pulverizer elbow on the boiler; 2. Know the correct maintenance strategy to increase the reliability of pulverizer pipes in boilers; 3. Simulate erosion due to coal particles in the pulverizer pipe using the Autodesk Simulation Computational Fluid Dynamics software program; 4. Analytical calculations of the erosion rate that occurs at the bend of the pulverizer pipe (elbow) in the boiler. The analysis was done by visual observation, hardness testing, metallographic observation, simulation of the ANSYS CFD program, and analytical calculation. The result of the ANSYS simulation showed that the main factor causing the leakage was erosion-corrosion. In the leaking area, the corrosion concentration was higher than in other areas, indicated by the red color in that area. From the calculation results, it was concluded that the largest erosion rate occurs at the angle of 200 with the value is 4.9548 x 10- 11 m3 / s, the smaller the pulverized coal’s angle of impact crashed the pulverizer pipe elbow, the greater the erosion.

The influence of the non-uniform airflow on the energy and cooling performance of the simplified electric vehicle front end cooling module

Electric vehicles (EVs) are viable alternatives to reduce greenhouse gas emissions and dependence on fossil energy resources. The front end cooling module (FECM), including the heat exchanger (HX), cooling fan, grille and other components, is indispensable for EVs. As the cooling airflow demand of EVs is smaller than that of traditional vehicles, the grille becomes flat and small so as to reduce the wind drag and improve the driving range, which causes more non-uniform airflow in the FECM. However, the influence of this change on the cooling fan has not been deeply researched so far.Thus, a simplified FECM model in this paper is designed to explore the influence of non-uniform airflow caused by different grilles. This study uses the computational fluid simulation (CFD) to get the numerical results and the airflow distribution inside the FECM, aiming to minimize the negative impact of the non-uniform airflow on the cooling fan and to reduce the power consumption, which has not been discussed by researches before. The results show that the target power consumption can be reduced by 5–18% through optimizing the grille, meanwhile meeting the mass flow rate required for cooling, which provides a reference for designers to refine parameters such as the grille size, and is beneficial for the energy saving and mileage improvement of EVs.

Aerodynamic Investigation on the Artefact “Bird of Saqqara”

Abstract Lost, technical knowledge of ancient cultures is being rediscovered in modern times during archaeological excavations. A presumed example of the innovative power of ancient cultures is the artefact “Bird of Saqqara”. In the context of this paper, the aerodynamic characteristics of the artefact are to be determined by a computational fluid simulation, in order to be able to make a statement about the actual flight suitability and to examine the theses of the pre-astronautics critically. Based on a 3D scan, a CAD model of the artefact is created and then a numerical flow simulation is performed. By varying the angle of attack, the dimensionless coefficients can be represented in corresponding polars. The results show that the artefact has a low maximum glide ratio and thus the glide properties are not sufficient for use as a handglider. The centre of gravity of the artefact is located at the trailing edge of the wing and behind the neutral point. The resulting longitudinal stability does not meet modern specifications. Asymmetric lift distribution in the spanwise direction results in uncontrolled roll. Consequently, the artefact cannot fly a straight path. Within the scope of this work, the connection between the “Bird of Saqqara” and an alleged knowledge of aerodynamics in ancient Egypt could not be confirmed.

Aerodynamic optimization for corner modification of octagonal-shape tall buildings using computational approach

Tall buildings are particularly susceptible to wind loads, which usually govern the design of lateral load-resisting systems. Therefore, wind loads must be adequately evaluated in the design of tall buildings. Aerodynamic modifications are highly effective tools for reducing wind loads. This paper investigates the effectiveness of corner modification optimization applied on an octagonal-plan-shaped model using computational fluid dynamic (CFD) simulation computational fluid dynamics associated with finite element analysis to alleviate wind-induced loads. Corner aerodynamic modifications such as chamfered, recessed, rounded, and fins are investigated. The corner modification was limited to a cutting radius of 6 m (12% of the building width) with a 0.5 m increment. The main considerations for this optimization procedure are top deflection, inter-story drifts, and the optimal number of additional floors. All corner modifications improve the building's performance, except fins corners resulting in adverse effects. In addition, 47 simulation examples from the case study are evaluated, presented, and discussed. With one additional floor, the optimum shape was able to reduce overall wind loads by 31.67%, resulting in a reduction in the structural response of 24.89% and 24.18% in maximum top deflection and inter-story drift, respectively.

Large-eddy simulation of buoyant airflow in an airborne pathogen transmission scenario

Indoor airflow patterns and the spreading of respiratory air were studied using the large-eddy simulation (LES) computational fluid dynamics (CFD) approach. A large model room with mixing ventilation was investigated. The model setup was motivated by super-spreading of the SARS-CoV-2 virus with a particular focus on a known choir practice setup where one singer infected all the other choir members. The room was heated with radiators at two opposite walls in the cold winter time. The singers produced further heat generating buoyancy in the room. The Reynolds number of the inflow air jets was set to Re=2750, corresponding to an air-changes-per-hour (ACH) value of approximately 3.5. The CFD solver was first validated after which a thorough grid convergence study was performed for the full numerical model room with heat sources. The simulations were then executed over a time of t=20 min to account for slightly more than one air change timescale for three model cases: (1) full setup with heat sources (radiators+singers) in the winter scenario, (2) setup without radiators in a summer scenario, and (3) theoretical setup without buoyancy (uniform temperature). The main findings of the paper are as follows. First, the buoyant flow structures were noted to be significant. This was observed by comparing cases 1/2 with case 3. Second, the dispersion of the respiratory aerosol concentration, modeled as a passive scalar, was noted to be significantly affected by the buoyant flow structures in cases 1–2. In particular, the aerosol cloud was noted to either span the whole room (cases 1–2) or accumulate in the vicinity of the infected singer (case 3). Turbulence was clearly promoted by the interaction of the upward/downward moving warmer/cooler air currents which significantly affected the dispersion of the respiratory aerosols in the room. The study highlights the benefits of high-resolution, unsteady airflow modeling (e.g. LES) for interior design which may consequently also impact predictions on exposure to potentially infectious respiratory aerosols.

Prediksi Laju Erosi Baja API 5L pada Pipa Siku Minyak dan Gas Menggunakan Komputasi Fluida

A large amount of oil and gas production needs to be followed by optimal pipeline maintenance. Most cases of pipe leaks are sudden in nature that able to cause losses over a long period of time. The gas consisting of sand particles able to increase erosion rate, especially at the pipe elbows. Cases of pipe leaks able to be prevented through routine inspections based on accurate erosion rate predictions. This study aims to predict the erosion rate of elbow piping systems using computational fluid simulations. The pipe material used is API 5L x60 and x70 steel. The simulation environment is arranged in such a way as to the reality on the oil and gas field. Methane gas containing sand particles with a hardness of 1100 HV is applied to this simulation. The simulation results prove that there is a relationship between the erosion rate, pipe hardness, and impact angle. Keywords: Erosion Rate Predictions, Elbow Pipe, and Hardness Pipe

Hazardous Area Reconstruction and Law Analysis of Coal Spontaneous Combustion and Gas Coupling Disasters in Goaf Based on DEM-CFD.

Coal spontaneous combustion and gas coupling disasters are the highest percentage of serious accidents in coal mines, causing the most serious disasters. China is one of the countries with the most serious coal spontaneous combustion and gas coupling disasters in goaf, and it is of great significance to explore the evolution law of coal spontaneous combustion and gas coupling disasters in goaf for disaster prevention and control. To study the three-dimensional spatial characteristics of the hazardous area of the coupling coal spontaneous combustion and gas disaster in goaf, a discrete element method-computational fluid dynamics (DEM-CFD)-based hazardous area reconstruction method was proposed. Taking a fully mechanized caving face of a coal mine in Shandong, China, as an example, first, the working face mining model was established by PFC3D, and the porosity of different horizontal and vertical positions of goaf after mining was extracted. Second, the porosity extracted was imported into computational fluid simulation software FLUENT by UDF. Finally, the distribution laws of oxygen and gas concentration during the real goaf mining process were simulated and analyzed. The results showed that the oxygen concentration in the intake roadway at a depth of 50.7 m in goaf decreased to 12%, and the gas concentration at a depth of 42.0 m in goaf increased to 16%. The oxygen concentration in the return airway roadway was reduced to 12% at 17.3 m depth in goaf, and the gas concentration increased to 16% at 6 m in the direction of goaf. The gas concentration was higher at the return air corner. The three-dimensional shapes of the hazardous area in goaf were constructed to satisfy the coupling of O2 concentration field, CH4 explosion limit concentration field, and fracture field and so were the laws of hazardous area analyzed qualitatively and quantitatively. It has important research significance for the rapid identification and determination of the coal spontaneous combustion and gas coupling disasters hazardous area.

Flow drag force contributes high bio-treatment efficiency in a circulating fluidized bed reactor: Mechanism of selective separation of functional decayed sludge

The diversity and expression of microbial function of activated sludge are influenced by combined effect of environmental factors and selective separation. The selective separation of sludge greatly depends on the design of reactor. The discharge of decayed microorganisms and the retain of active microorganisms cannot be realized through sedimentation and reflux of the activated sludge in the conventional secondary sedimentation tank. Thus, this study proposed a strategy for in-situ selective separation of activated sludge by means of the circulating flow field. The fluid field in the fluidized bed reactor was found to influence the distribution of activated sludge with different physical properties, biological properties, and functions. The sludge with various particle sizes showed different bio-characteristics. Then, based on the cumulative distribution of mean floc size, three kinds of component sludge with different floc sizes (sludge-a: 10.56–81.42 μm, 28.3 %; sludge-b: 81.42–104.63 μm, 26.1 %; and sludge-c: 104.63–257.94 μm, 45.6 %) were hypothesized to constitute all the sludge in the fluidized bed reactor for simplification of heterogeneous sludge. Finally, computational fluid dynamical and simulation calculations were used to reveal the impact of selective sludge discharge on bio-treatment efficiency. The results indicated that the bio-treatment efficiency could be improved by more than 5.0 % based on the selective discharge of decayed sludge with the same input of energy. This work demonstrated a principle that a fluid field could be used to identify functionally decayed sludge in a fluidized bed reactor for wastewater treatment. The principle could play an important role in identification and separation of microbial function decayed sludge for improving the bio-reaction efficiency, energy utilization rate and stability of reactor.

Domain expert evaluation of advanced visual computing solutions and 3D printing for the planning of the left atrial appendage occluder interventions.

Advanced visual computing solutions and three-dimensional (3D) printing are moving from engineering to clinical pipelines for training, planning, and guidance of complex interventions. 3D imaging and rendering, virtual reality (VR), and in-silico simulations, as well as 3D printing technologies provide complementary information to better understand the structure and function of the organs, thereby improving and personalizing clinical decisions. In this study, we evaluated several advanced visual computing solutions, such as web-based 3D imaging visualization, VR, and computational fluid simulations, together with 3D printing, for the planning of the left atrial appendage occluder (LAAO) device implantations. Six cardiologists tested different technologies in pre-operative data of five patients to identify the usability, limitations, and requirements for the clinical translation of each technology through a qualitative questionnaire. The obtained results demonstrate the potential impact of advanced visual computing solutions and 3D printing to improve the planning of LAAO interventions as well as the need for their integration into a single workflow to be used in a clinical environment.