期刊文献+
共找到8篇文章
< 1 >
每页显示 20 50 100
Three-Dimensional Convection in an Inclined Porous Layer Subjected to a Vertical Temperature Gradient
1
作者 Ivan Shubenkov Tatyana Lyubimova Evgeny Sadilov 《Fluid Dynamics & Materials Processing》 EI 2024年第9期1957-1970,共14页
In this paper,we study the onset and development of three-dimensional convection in a tilted porous layer saturated with a liquid.The layer is subjected to a gravitational field and a strictly vertical temperature gra... In this paper,we study the onset and development of three-dimensional convection in a tilted porous layer saturated with a liquid.The layer is subjected to a gravitational field and a strictly vertical temperature gradient.Typically,problems of thermal convection in tilted porous media saturated with a liquid are studied by assuming constant different temperatures at the boundaries of the layer,which prevent these systems from supporting conductive(non-convective)states.The boundary conditions considered in the present work allow a conductive state and are representative of typical geological applications.In an earlier work,we carried out a linear stability analysis of the conductive state.It was shown that at any layer tilt angles,the most dangerous type of disturbances are longitudinal rolls.Moreover,a non-zero velocity component exists in z-direction.In the present work,threedimensional non-linear convection regimes are studied.The original three-dimensional problem is reduced to two-dimensional one with an analytical expression for the velocity z-component v_(z)=v_(z)(x,y).It is shown that the critical Rayleigh number values obtained through numerical solutions of the obtained 2D problem by a finite difference method for different layer inclination angles,are in a good agreement with those predicted by the linear theory.The number of convective rolls realized in nonlinear calculations also fits the linear theory predictions for a given cavity geometry.Calculations carried out at low supercriticalities show that a direct bifurcation takes place.With increasing supercriticality,no transitions to other convective regimes are detected.The situation studied in this problem can be observed in oil-bearing rock formations under the influence of a geothermal temperature gradient,where the ensuing fluid convection can affect the distribution of oil throughout the layer. 展开更多
关键词 Thermal convection inclined layer porous media vertical temperature gradient
下载PDF
Numerical investigation of temperature gradient-induced thermal stress for steel–concrete composite bridge deck in suspension bridges 被引量:7
2
作者 WANG Da DENG Yang +1 位作者 LIU Yong-ming LIU Yang 《Journal of Central South University》 SCIE EI CAS CSCD 2018年第1期185-195,共11页
A3D finite element model(FEM)with realistic field measurements of temperature distributions is proposed to investigate the thermal stress variation in the steel–concrete composite bridge deck system.First,a brief lit... A3D finite element model(FEM)with realistic field measurements of temperature distributions is proposed to investigate the thermal stress variation in the steel–concrete composite bridge deck system.First,a brief literaturereview indicates that traditional thermal stress calculation in suspension bridges is based on the2D plane structure with simplified temperature profiles on bridges.Thus,a3D FEM is proposed for accurate stress analysis.The focus is on the incorporation of full field arbitrary temperature profile for the stress analysis.Following this,the effect of realistic temperature distribution on the structure is investigated in detail and an example using field measurements of Aizhai Bridge is integrated with the proposed3D FEM model.Parametric studies are used to illustrate the effect of different parameters on the thermal stress distribution in the bridge structure.Next,the discussion and comparison of the proposed methodology and simplified calculation method in the standard is given.The calculation difference and their potential impact on the structure are shown in detail.Finally,some conclusions and recommendations for future bridge analysis and design are given based on the proposed study. 展开更多
关键词 suspension bridge steel–concrete composite bridge deck vertical temperature gradient finite element method thermal stress
下载PDF
Experimental study on thermal environment in large-space building with low sidewall air supply
3
作者 黄晨 刘稳 +2 位作者 邹志军 任荣 陈雷 《Journal of Southeast University(English Edition)》 EI CAS 2010年第2期270-273,共4页
The thermal environmental characteristics are experim-entally studied in terms of different air supply volumes and outdoor meteorological parameters in a large-space building which is air conditioned with a low sidewa... The thermal environmental characteristics are experim-entally studied in terms of different air supply volumes and outdoor meteorological parameters in a large-space building which is air conditioned with a low sidewall air supply.The experimental results show that the indoor vertical temperature distributions under different condition are similar.The maximum vertical temperature difference(MVTD)is up to about 20 ℃,and it linearly changes with the sol-air temperature.The indoor vertical temperature gradients(VTGs)in the upper,central and lower zones are different.The influence of the sol-air temperature on the VTGs in the upper and the lower zones is greater than that in the central zone.The characteristics of the VTGs in the three zones affected by the air supply volume are the same as those affected by the sol-air temperature.Besides,because of the small air velocity,the predicted mean vote(PMV)on comfort in the occupied zone is slightly high and the air temperature difference between the head and the ankle is usually more than 3 ℃. 展开更多
关键词 large space building low sidewall air supply vertical temperature gradient thermal environment
下载PDF
Analytical models for evaluating buoyancy-driven ventilation due to stack effect in a shaft considering heat transfer from shaft interior boundaries 被引量:1
4
作者 阳东 李百战 +1 位作者 杜涛 李楠 《Journal of Central South University》 SCIE EI CAS 2012年第3期651-656,共6页
Stack effect is a dominant driving force for building natural ventilation.Analytical models were developed for the evaluation of stack effect in a shaft,accounting for the heat transfer from shaft interior boundaries.... Stack effect is a dominant driving force for building natural ventilation.Analytical models were developed for the evaluation of stack effect in a shaft,accounting for the heat transfer from shaft interior boundaries.Both the conditions with constant heat flux from boundaries to the airflow and the ones with constant boundary temperature were considered.The prediction capabilities of these analytical models were evaluated by using large eddy simulation(LES) for a hypothetical shaft.The results show that there are fairly good agreements between the predictions of the analytical models and the LES predictions in mass flow rate,vertical temperatures profile and pressure difference as well.Both the results of analytical models and LES show that the neutral plane could locate higher than one half of the shaft height when the upper opening area is identical with the lower opening area.Further,it is also shown that the analytical models perform better than KLOTE's model does in the mass flow rate prediction. 展开更多
关键词 stack effect theoretical analysis large eddy simulation vertical temperature distribution heat transfer
下载PDF
Effects of Climate Variability on Habitat Range and Distribution of Chub Mackerel in the East China Sea 被引量:3
5
作者 YU Wei WEN Jian +3 位作者 CHEN Xinjun LI Gang LI Yuesong ZHANG Zhong 《Journal of Ocean University of China》 SCIE CAS CSCD 2021年第6期1483-1494,共12页
Spatio-temporal distribution of chub mackerel Scomber japonicus is strongly susceptible to climate variability.In this study,a weighting-based habitat suitability index(HSI)model was established to assess the impacts ... Spatio-temporal distribution of chub mackerel Scomber japonicus is strongly susceptible to climate variability.In this study,a weighting-based habitat suitability index(HSI)model was established to assess the impacts of Pacific Decadal Oscillation(PDO)on habitat range and distribution of S.japonicus in the East China Sea(ECS)using vertical water temperature at depths of 2.5 m,25 m and 50 m.Results showed that the optimal HSI model selected from ten weighting scenarios can yield reliable predictions.Correlation analysis revealed a significant negative relationship between the PDO index and water temperature anomaly at different depths.The water temperatures at three different layers on the fishing ground of S.japonicus tended to be low in the warm PDO phase and high in the cold PDO phase,respectively.The range of suitable habitats and its spatial distribution exhibited large differences between the warm and cold PDO regimes.During a warm PDO phase,vertical water temperature became cool,and the monthly preferred water temperature at each depth for S.japonicus shifted southeastward.Consequently,habitat quality dramatically decreased,and suitable habitat ranges also reduced and moved southeastward.Conversely,in a cool PDO phase,with the warmer vertical water temperature and northwestward shift of the preferred water temperature,the suitable habitats enlarged and migrated in the same direction.Our findings indicate that the PDO produced significant impacts on habitat range and distribution of S.japonicus in the East China Sea. 展开更多
关键词 Scomber japonicus habitat pattern vertical water temperature Pacific Decadal Oscillation the East China Sea
下载PDF
Climate-Related Variations in Autumn Cohort of Japanese Common Squid Todarodes pacificus 被引量:1
6
作者 YU Wei FENG Zhiping +2 位作者 CHEN Bingjian WEI Zhenhua FENG Yinyin 《Journal of Ocean University of China》 SCIE CAS CSCD 2023年第2期490-500,共11页
The Japanese common squid Todarodes pacificus is widely distributed in the Sea of Japan,the East China Sea and the Northwest Pacific Ocean,and is largely exploited by the Asia-Pacific countries.In this study,the impac... The Japanese common squid Todarodes pacificus is widely distributed in the Sea of Japan,the East China Sea and the Northwest Pacific Ocean,and is largely exploited by the Asia-Pacific countries.In this study,the impacts of regime shift of the Pacific Decadal Oscillation(PDO)during 1977-2015 on the autumn cohort of T.pacificus were assessed by examining the variations in vertical water temperatures at depths of 0 m(Temp_0 m),50 m(Temp_50 m)and 100 m(Temp_100 m)and the distribution pattern of preferred spawning ground(SSG).Spatial and temporal correlation analysis revealed that the PDO index exhibited a significantly negative relationship with vertical water temperatures at different depths and was negatively related to catch-per-unit-effort(CPUE)and stock biomass of T.pacificus.In addition,water temperatures in the specific three water layers were positively associated with CPUE.The PDO regime shift strongly affected the thermal condition and spawning ground of T.pacificus.Comparing to the negative PDO,the waters from the surface to the deep became cool in the positive PDO phase;correspondingly,the area of SSG largely contracted at different depths.Consequently,the CPUE and stock biomass of T.pacificus profoundly decreased.From the results it can be concluded that the PDO regime shift-driven changes in vertical thermal condition and SSG ranges can yield substantial impacts on T.pacificus abundance. 展开更多
关键词 Todarodes pacificus vertical water temperature spawning ground Pacific Decadal Oscillation regime shift
下载PDF
Thermal sensation and percentage of dissatisfied in thermal environments with positive and negative vertical air temperature differences
7
作者 Yuxin Wu Sheng Zhang +1 位作者 Hong Liu Yong Cheng 《Energy and Built Environment》 2023年第6期629-638,共10页
Considering the percentage of dissatisfied due to local thermal sensation(PD LTSV),a vertical air temperature difference(ΔT_(d))threshold of about 3°C was recommended in standards.However,some novel air distribu... Considering the percentage of dissatisfied due to local thermal sensation(PD LTSV),a vertical air temperature difference(ΔT_(d))threshold of about 3°C was recommended in standards.However,some novel air distribution methods might create large positive(which means the head warmer than the feet,vice versa)or negativeΔT_(d),with no suitable proved criteria to be used.In this study,sixteen subjects were seated in a climatic box placed in a climate chamber to evaluate thermal sensation and percentage of dissatisfied with negative and positiveΔT_(d) in different whole-body thermal conditions.Air temperatures were controlled independently at the upper and lower body parts,with 13 different air temperature sets combined with 22°C,25°C,28°C,and 31°C(i.e.-9°C≤ΔT_(d)≤9°C).Results showed that subjects were more thermally sensitive at the upper body and with positiveΔT_(d) than at the lower body or with negativeΔT_(d).The 80%acceptableΔT_(d) range is about-8 to 7°C in overall neutral(TSV=0),-7°C to 6°C in slightly cool(TSV=-0.5)conditions,which is wider than-3 to 3°C in slightly warm conditions(TSV=+0.5).By considering the factors of both TSV andΔT_(d),a new overall percentage of dissatisfied index(OPD P)was proposed.Case studies show that the new OPD P index is more precise and suitable for the evaluations of different air distributions to predict overall percentage of dissatisfied in thermal environments with vertical air temperature difference. 展开更多
关键词 vertical air temperature difference Thermal sensation Thermal comfort Percentage of dissatisfied Air distribution
原文传递
Simulation of Velocity and Temperature Distributions of Displacement Ventilation System with Single or Double Heat Sources
8
作者 Wenfei WU Xuan Wu +1 位作者 Yanhui Feng Xinxin Zhang 《Journal of Thermal Science》 SCIE EI CAS CSCD 2007年第2期155-158,共4页
In order to obtain a better understanding of flow characteristics of displacement ventilation, the three-dimensional numerical models are developed using the CFD technology. The numerical simulation results are verifi... In order to obtain a better understanding of flow characteristics of displacement ventilation, the three-dimensional numerical models are developed using the CFD technology. The numerical simulation results are verified by experiments, based on this, the velocity and temperature distribution of three-dimensional displacement ventilation system with single and double heat sources are studied. Velocity and temperature fields under two different cases of heat source are analyzed and compared. The numerical results show that there are three layers in vertical temperature fields of displacement ventilation system with single or double heat sources, and the vertical temperature distribution of single heat source is different from that of double heat sources. When indoor load is large, the comfort requirement of people indoor can't be satisfied with displacement ventilation system only, thus an additional refrigeration system is necessary. Furthermore, under the condition of two heat sources, the displacement ventilation parameters can't be computed simply according to single heat source inlet parameters, therefore the interaction between heat sources should be considered. 展开更多
关键词 displacement ventilation velocity distribution vertical temperature distribution CFD
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部