scholarly journals CFD NUMERICAL SIMULATION OF TEMPERATURE AND AIRFLOW DISTRIBUTION IN PIGSTY BASED ON GRID INDEPENDENCE VERIFICATION

2020 ◽  
Vol 61 (2) ◽  
pp. 241-250 ◽  
Author(s):  
Min Jin ◽  
Chunguang Wang ◽  
Pengpeng Wang
Keyword(s):  
Numerical Simulation ◽  
Relative Error ◽  
Mesh Generation ◽  
Average Relative Error ◽  
Airflow Velocity ◽  
The Third ◽  
Airflow Distribution ◽  
Cfd Numerical Simulation ◽  
Grid Independence

Grid independence verification was implemented to improve the reliability of CFD numerical simulation in pigsty. The effects of four different grid numbers on airflow and temperature simulation of 0.4m, 1.0m and 1.6m heights were compared. The results showed that the third method of mesh generation and the grid numbers about 2.09 million were more suitable for this pigsty model. The average relative error of airflow velocity and temperature between the simulated and the measured alues were 7.1% and 3.8% respectively, the average NMSE were 0.0012 and 0.0066 respectively. Therefore, grid independence verification is of great significance for CFD numerical simulation.

Impact Simulation of a Crashworthy Composite Fuselage Section with Energy-Absorbing Floor

2014 ◽  
Vol 529 ◽  
pp. 102-107
Author(s):  
Hai Bo Luo ◽  
Ying Yan ◽  
Xiang Ji Meng ◽  
Tao Tao Zhang ◽  
Zu Dian Liang
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Dynamic Response ◽  
Relative Error ◽  
High Strength ◽  
Computer Code ◽  
Impact Simulation ◽  
Average Acceleration ◽  
Simulation Results ◽  
Energy Absorbing

A 7.8m/s vertical drop simulate of a full composite fuselage section was conducted with energy-absorbing floor to evaluate the crashworthiness features of the fuselage section and to predict its dynamic response to dummies in future. The 1.52m diameter fuselage section consists of a high strength upper fuselage frame, one stiff structural floor and an energy-absorbing subfloor constructed of Rohacell foam blocks. The experimental data from literature [6] were analyzed and correlated with predictions from an impact simulation developed using the nonlinear explicit transient dynamic computer code MSC.Dytran. The simulated average acceleration did not exceed 13g, by contrast with experimental results, whose relative error is less than 11%. The numerical simulation results agree with experiments well.

scholarly journals Study on the Efficiency and Dynamic Characteristics of an Energy Harvester Based on Flexible Structure Galloping

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6548
Author(s):  
Peng Liao ◽  
Jiyang Fu ◽  
Wenyong Ma ◽  
Yuan Cai ◽  
Yuncheng He
Keyword(s):  
Numerical Simulation ◽  
Wind Speed ◽  
Physical Model ◽  
Energy Harvester ◽  
High Efficiency ◽  
Lateral Displacement ◽  
Maximum Output Power ◽  
Flexible Structure ◽  
Maximum Output ◽  
Cfd Numerical Simulation

According to the engineering phenomenon of the galloping of ice-coated transmission lines at certain wind speeds, this paper proposes a novel type of energy harvester based on the galloping of a flexible structure. It uses the tension generated by the galloping structure to cause periodic strain on the piezoelectric cantilever beam, which is highly efficient for converting wind energy into electricity. On this basis, a physical model of fluid–structure interaction is established, and the Reynolds-averaged Navier–Stokes equation and SST K -ω turbulent model based on ANSYS Fluent are used to carry out a two-dimensional steady computational fluid dynamics (CFD) numerical simulation. First, the CFD technology under different grid densities and time steps is verified. CFD numerical simulation technology is used to simulate the physical model of the energy harvester, and the effect of wind speed on the lateral displacement and aerodynamic force of the flexible structure is analyzed. In addition, this paper also carries out a parameterized study on the influence of the harvester’s behavior, through the wind tunnel test, focusing on the voltage and electric power output efficiency. The harvester has a maximum output power of 119.7 μW/mm3 at the optimal resistance value of 200 KΩ at a wind speed of 10 m/s. The research results provide certain guidance for the design of a high-efficiency harvester with a square aerodynamic shape and a flexible bluff body.

scholarly journals Predicting Indoor Temperature Distribution Based on Contribution Ratio of Indoor Climate (CRI) and Mobile Sensors

Buildings ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 458
Author(s):  
Yanan Zhao ◽  
Zihan Zang ◽  
Weirong Zhang ◽  
Shen Wei ◽  
Yingli Xuan
Keyword(s):  
Temperature Distribution ◽  
Relative Error ◽  
Prediction Accuracy ◽  
Prediction Method ◽  
Mobile Sensors ◽  
Average Relative Error ◽  
Contribution Ratio ◽  
Mobile Sensor ◽  
Indoor Climate ◽  
Indoor Temperature

In practical building control, quickly obtaining detailed indoor temperature distribution is necessary for providing satisfying personal comfort and improving building energy efficiency. The aim of this study is to propose a fast prediction method for indoor temperature distribution without knowing the thermal boundary conditions in practical applications. In this method, the index of contribution ratio of indoor climate (CRI), which represents the independent contribution of each heat source to the temperature distribution, has been combined with the air temperature collected by one mobile sensor at the height of the working area. Based on a typical office model, the effectiveness of using mobile sensors was discussed, and the influence of its acquisition height and acquisition distance on the prediction accuracy was analyzed as well. The results showed that the proposed prediction method was effective. When the sensors fixed on the wall were used to predict the indoor temperature distribution, the maximum average relative error was 27.7%, whereas when the mobile sensor was used to replace the fixed sensors, the maximum average relative error was 4.8%. This indicates that using mobile sensors with flexible acquisition location can help promote both reliability and accuracy of temperature prediction. In the human activity area, data from a set of mobile sensors were used to predict the temperature distribution at four heights. The prediction accuracy was 2.1%, 2.1%, 2.3%, and 2.7%, respectively. However, the influence of acquisition distance of mobile sensors on prediction accuracy cannot be ignored. The distance should be large enough to disperse the distribution of the acquisition points. Due to the influence of airflow, some distance between the acquisition points and the room boundaries should be given.

Research on the CFD numerical simulation of flash boiling atomization

Energy ◽  
2018 ◽  
Vol 165 ◽  
pp. 768-781 ◽  
Author(s):  
Rongshan Bi ◽  
Chen Chen ◽  
Jiansong Li ◽  
Xinshun Tan ◽  
Shuguang Xiang
Keyword(s):  
Numerical Simulation ◽  
Cfd Numerical Simulation ◽  
Flash Boiling

Numerical Simulation Study on Battery-Casing Sealing Considering Rubber Aging

2020 ◽  
Vol 36 (6) ◽  
pp. 955-969
Author(s):  
Yijie Huang ◽  
Fei Guo ◽  
Yuchao Ke ◽  
Fangyong Wu ◽  
Xiaohong Jia ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Porous Media ◽  
Circular Arc ◽  
Sealing Material ◽  
Sealing Performance ◽  
Porous Media Model ◽  
New Energy ◽  
Key Factor ◽  
Grid Independence ◽  
New Energy Vehicles

ABSTRACTBattery-casing sealing is the key factor for secure travel of new energy vehicles. We constructed a relatively accurate mechanical-simulation model by selecting a constitutive model, analyzing the influence of thermal elongation, verifying the grid-independence and comparing numerically by the pressure-measurement film on the basis of studying the physical performance of a certain type of sealing material that had been used in battery-casings after aging. Based on a porous-media model and combined with changes of macroscopic and microscopic contact characteristics of materials at different times after aging, the evolution rule of sealing performance with time was analyzed quantitatively by calculating the leakage. By analyzing the structure of circular arc bulge on the surface of sealing material, the radius of circular arc bulge with better sealing performance was obtained, which could reduce the leakage of sealing structure during the material’s lifecycle.

scholarly journals Numerical rainfall simulation with different spatial and temporal evenness by using WRF multi-physics ensembles

2016 ◽  
Author(s):  
Jiyang Tian ◽  
Jia Liu ◽  
Chuanzhe Li ◽  
Fuliang Yu
Keyword(s):  
Relative Error ◽  
Wrf Model ◽  
Temporal Distribution ◽  
Northern China ◽  
Rainfall Simulation ◽  
Average Relative Error ◽  
Storm Events ◽  
Cumulative Rainfall ◽  
Study Sites

Abstract. The Weather Research and Forecasting (WRF) model is used in this study to simulate six storm events in two semi-humid and semi-arid catchments of Northern China. The six storm events are classified into four types based on the rainfall evenness in the spatial and temporal dimensions. Two microphysics, two planetary boundary layers (PBL) and three cumulus parameterizations are combined to develop 12 physical ensembles for rainfall generation. The WRF model performs the best for Type 1 event with relatively even distributions of rainfall in both space and time. The average relative error (ARE) for the cumulative rainfall amount is 16.98 %. For the spatial rainfall simulation, the lowest root mean square error (RMSE) is found with event II (0.3989) which has the most even spatial distribution, and for the temporal simulation the lowest RMSE is found with event I (1.0171) which has the most even temporal distribution. It is found to be the most difficult to reproduce the very convective storm with uneven spatiotemporal distributions (Type 4 event) and the average relative error (ARE) for the cumulative rainfall amounts is up to 68.07 %. The RMSE results of Event III with the most uneven spatial and temporal distribution are 0.9363 for the spatial simulation and 2.7769 for the temporal simulation, which are much higher than the other storms. The general performance of the current WRF physical parameterisations is discussed. The Betts-Miller-Janjic (BMJ) is found to be unsuitable for rainfall simulation in the study sites. For Type 1, 2, and 4 storms, ensemble 4 performs the best. For Type 3 storms, ensemble 5 and 7 are the better choice. More guidance is provided for choosing among the physical parameterisations for accurate rainfall simulations of different storm types in the study area.

Sign in / Sign up

Export Citation Format

Share Document