Network flow modeling via lattice-Boltzmann based channel conductance     

Yelena Sholokhova  Daesang KimW. Brent Lindquist 《Advances in water resources》2009

Lattice-Boltzmann (LB) computations of single phase, pore-to-pore conductance are compared to models in which such conductances are computed via standard pore body–channel–pore body series resistance (SR), with the conductance of each individual element (pore body, channel) based on geometric shape factor measurements. The LB computations, based upon actual channel geometry derived from X-ray computed tomographic imagery, reveal that the variation in conductance for channels having similar shape factor is much larger than is adequately captured by the geometric models. Fits to the dependence of median value of conductance versus shape factor from the LB-based computations show a power law dependence of higher power than that predicted by the geometric models. We introduce two network flow models based upon the LB conductance computations: one model is based upon LB computations for each pore-to-pore connection; the second is based upon a power law fit to the relationship between computed conductance and throat shape factor. Bulk absolute permeabilities for Fontainebleau sandstone images are computed using the SR-based network models and the two LB-based models. Both LB-based network models produce bulk absolute permeability values that fit published data more accurately than the SR-based models.  相似文献   

不同泥质分布形式泥质砂岩导电规律实验研究   总被引：2，自引：1，他引：1       下载免费PDF全文

宋延杰  唐晓敏  于宝 《地球物理学进展》2009,24(6):2186-2193

本文利用人工制作的不同含量分散泥质和层状泥质砂岩岩心样品,测量不同矿化度和不同含油饱和度的岩心电阻率,从实验角度研究了不同泥质分布形式和含量的岩心导电规律,结果表明,泥质分布形式或含量不同,则泥质砂岩导电规律不同.基于层状泥质与分散泥质砂岩的并联导电实验规律,以及分散粘土和地层水混合物的导电规律可用HB电阻率方程描述,建立了考虑泥质分布形式影响的泥质砂岩电阻率模型.通过1组不同泥质分布形式泥质砂岩人造岩心实验数据的测试,表明该模型可以描述分散泥质砂岩、层状泥质砂岩和混合泥质砂岩地层的导电规律.分散泥质,层状泥质,人造岩样,实验测量,并联导电,HB方程,电阻率模型  相似文献   

任意三角形毛细管中水力传导率与形状因子关系研究     

陶军  姚军  李爱芬  赵秀才 《岩土力学》2007,28(8):1729-1732

孔隙级网络模型可以用简单几何体来代表真实的孔隙孔喉,以分析流体在这些简单几何体中的流动,具有重要的意义。利用有限元法对任意三角形截面管中的单相和油水两相流动的速度场进行了求解,后由速度场进一步计算出了水力传导率。研究了水力传导率与形状因子之间的关系,结果表明,单相流水力传导率与形状因子近似呈直线关系,而油水两相流时,水力传导率除与形状因子有关外,还随着角落半角和油水接触角的变化而变化。  相似文献   

表皮环割对花花柴(Kareliniacaspica)水势及光合参数的短期影响     

唐钢梁  李向义  林丽莎  李磊  鲁建荣 《中国沙漠》2014,34(6):1527-1536

生长在塔克拉玛干沙漠南缘的植物在生长季常遭受虫害和放牧的影响,频繁的干扰在很大程度上限制了该地区植物的生存和生长.以塔克拉玛干沙漠南缘策勒绿洲外围花花柴(Karelinia caspica)为试验材料,模拟干扰对于花花柴生理状况的短期影响,设置了对照(正常枝条)、中度环割(表皮环割50%)、重度环割(表皮环割100%),观测了环割后10 d内花花柴气孔导度、水势、光合色素、叶绿素荧光等在不同环割条件下的变化特征.结果显示:(1)除了类胡萝卜素(Car)含量外,中度环割对花花柴各项生理参数的影响不明显;(2)重度环割能够明显降低花花柴气孔导度、清晨水势和正午水势、叶绿素(Cal)含量和类胡萝卜素(Car)含量;(3)重度环割使得花花柴的光合原初反应遭到抑制,光系统Ⅱ(PSⅡ)结构和功能遭到损害,活性降低,光合器官对光能的吸收、传递、转化和电子捕获等过程也遭到抑制,用于耗散的能量显著增多.整体来看,重度环割下的花花柴短期内各项生理参数均出现显著降低,而中度环割下花花柴各项生理参数短期内变化不大.当人为或者昆虫、野兔等对花花柴表皮产生机械损伤时,表皮部分损伤的植物也许可以通过自身修复,使得各项生理机能恢复正常,而表皮遭受重度破坏的植物会随着时间的推移趋向于死亡.在荒漠化防治过程中,我们应该尽量避免花花柴的表皮被全部剥蚀.  相似文献   

Canopy conductance in a two‐storey Siberian boreal larch forest,Russia          下载免费PDF全文

Bao‐Lin Xue  Zhanling Li  Xin‐An Yin  Tieliang Zhang  Shin'ichi Iida  Kyoichi Otsuki  Takeshi Ohta  Qinghua Guo 《水文研究》2015,29(6):1017-1026

A larch forest in eastern Siberia was characterized by the presence of two distinct storeys, the overstorey with a small leaf area index (LAI) and a dense understorey with a relatively large LAI. To understand the roles of the overstorey and understorey in forest–atmosphere water exchange, canopy conductance (G_c), a critical parameter used in determining the energy and mass exchange, was calculated on the basis of latent heat flux above the overstorey and understorey, measured separately. Results showed that G_c for the overstorey (G_co) and understorey (G_cu) experienced different seasonal fluctuations. G_co was smaller than G_cu during periods of leaf expansion and leaf fall and showed an increasing trend until 1 month after the onset of leaf expansion. In contrast, a sharp decrease in G_co was observed immediately before onset of leaf fall. Furthermore, G_co was slightly larger than G_cu during the fully foliated period. A simple model using solar radiation and vapour pressure deficit (D) as inputs successfully reproduced the G_c in fully foliated periods with acceptable accuracy. Furthermore, both the understorey and overstorey in this study have a large reference G_c (G_c at D = 1 KPa) than their counterparts of other boreal forests and would not be able to sustain a constant leaf–soil water potential difference as D increases. We speculated that this confers the forest with an advantage allowing it to be able to sustain carbon assimilation during large D days and thus provides for the survival of the ecosystem during the short growing season at this site. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

淮北棉区花铃期冠层不同高度叶片光合特性的差异     

周晓冬  李永秀  张雪松  申双和 《南京气象学院学报》2009,32(5):673-676

基于多层二叶模型,在自然群体条件下,将棉花冠层分为上、中、下三层,研究淮北棉花花铃期冠层上、中、下层,阴叶（无直射光照射）与阳叶（有直射光照射）的光合特性的差异。结果表明,同一高度阳叶的光量子通量密度与光合速率显著大于阴叶;不同高度叶片光量子通量密度与光合速率均表现为上层阳叶〉中层阳叶〉下层阳叶,上层阴叶〉中层阴叶〉下层阴叶;上层阳叶气孔导度大于阴叶,中、下层阴、阳叶的气孔导度无显著差异;上部叶片气孔导度〉中部叶片〉下部叶片;同一高度阳叶胞间二氧化碳浓度显著小于阴叶,随着冠层深度（形态学自上而下）的增加,两者差异增大;不同高度叶片胞间二氧化碳浓度随着冠层深度的增加,呈增加趋势,阳叶差异不显著,阴叶差异显著。  相似文献   

全波形时间域航空电磁探测分辨率   总被引：6，自引：0，他引：6  

嵇艳鞠  栾卉  李肃义  万玲  王远  许洋钺  李丽  林君 《吉林大学学报(地球科学版)》2011,41(3):885-891

时间域航空电磁系统的传统记录方式存在不能探测高导异常等不足。以导电薄板为模型,研究了梯形波激励、全波形记录方式下的探测分辨率。采用等效涡流环近似方法,在计算了任意位置两线圈互感的基础上,实现了薄板电流关断期间和断开期间感应电动势的数值计算。数值计算表明:当存在覆盖层时,如果测量系统最小分辨率为5 nV/m2,在电流断开期间可检测目标体电导为1~400 S,在电流关断期间可检测目标体电导为0.1~1 000 S。时间域航空电磁系统采用全波形测量,可以拓宽电磁系统检测异常电导的分辨率孔径。  相似文献   

Electromagnetic induction in thin sheets: integral equations and model studies in two dimensions     

U. Schmucker 《Geophysical Journal International》1995,121(1):173-190

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Relationship between canopy height and the reference value of surface conductance for closed coniferous stands     

Hikaru Komatsu 《水文研究》2003,17(12):2503-2512

When estimating the dry‐canopy evaporation rate of coniferous stands using the Penman–Monteith equation, it is crucial to determine the reference value of surface conductance G_s. This paper examines the relationship between canopy height and the reference value of G_s based on the maximum value of G_s with a vapour pressure deficit ≥ 1·0 kPa, ?_{s max}. There is a clear correlation between canopy height and ?_{s max} when the projected leaf area index ≥3·0. This suggests that using this relationship will enable more accurate determination of the reference value of G_s for closed stands. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Geothermal solute flux monitoring and the source and fate of solutes in the Snake River,Yellowstone National Park,WY     

《Applied Geochemistry》2016

The combined geothermal discharge from over 10,000 features in Yellowstone National Park (YNP) can be can be estimated from the Cl flux in the Madison, Yellowstone, Falls, and Snake Rivers. Over the last 30 years, the Cl flux in YNP Rivers has been calculated using discharge measurements and Cl concentrations determined in discrete water samples and it has been determined that approximately 12% of the Cl flux exiting YNP is from the Snake River. The relationship between electrical conductivity and concentrations of Cl and other geothermal solutes was quantified at a monitoring site located downstream from the thermal inputs in the Snake River. Beginning in 2012, continuous (15 min) electrical conductivity measurements have been made at the monitoring site. Combining continuous electrical conductivity and discharge data, the Cl and other geothermal solute fluxes were determined. The 2013–2015 Cl fluxes (5.3–5.8 kt/yr) determined using electrical conductivity are comparable to historical data. In addition, synoptic water samples and discharge data were obtained from sites along the Snake River under low-flow conditions of September 2014. The synoptic water study extended 17 km upstream from the monitoring site. Surface inflows were sampled to identify sources and to quantify solute loading. The Lewis River was the primary source of Cl, Na, K, Cl, SiO₂, Rb, and As loads (50–80%) in the Snake River. The largest source of SO₄ was from the upper Snake River (50%). Most of the Ca and Mg (50–55%) originate from the Snake Hot Springs. Chloride, Ca, Mg, Na, K, SiO₂, F, HCO₃, SO₄, B, Li, Rb, and As behave conservatively in the Snake River, and therefore correlate well with conductivity (R² ≥ 0.97).  相似文献