A finite-element model of a two-dimensional, single-phase heat transport in a porous medium

Frank, Andreas O., C. J. Charles Chuong, and Robert L. Johnson. A finite-element model of oxygen diffusion in the pulmonary capillaries. J. Appl. Physiol. 82(6): 2036–2044, 1997.—We determined the overall pulmonary diffusing capacity (Dl) and the diffusing capacities of the alveolar membrane (Dm) and the red blood cell (RBC) segments (De) of the diffusional pathway for O2 by using a two-dimensional finite-element model developed to represent the sheet-flow characteristics of pulmonary capillaries. An axisymmetric model was also considered to assess the effect of geometric configuration. Results showed the membrane segment contributing the major resistance, with the RBC segment resistance increasing as O2 saturation ([Formula: see text]) rises during the RBC transit: RBC contributed 7% of the total resistance at the capillary inlet ([Formula: see text] = 75%) and 30% toward the capillary end ([Formula: see text] = 95%) for a 45% hematocrit (Hct). Both Dm and Dlincreased as the Hct increased but began approaching a plateau near an Hct of 35%, due to competition between RBCs for O2 influx. Both Dm and Dl were found to be relatively insensitive (2∼4%) to changes in plasma protein concentration (28∼45%). Axisymmetric results showed similar trends for all Hct and protein concentrations but consistently overestimated the diffusing capacities (∼2.2 times), primarily because of an exaggerated air-tissue barrier surface area. The two-dimensional model correlated reasonably well with experimental data and can better represent the O2 uptake of the pulmonary capillary bed.

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A NEW TWO-DIMENSIONAL FINITE ELEMENT MODEL FOR THE SHALLOW WATER EQUATIONS USING A LAGRANGIAN FRAMEWORK CONSTRUCTED ALONG FLUID PARTICLE TRAJECTORIES

International Journal for Numerical Methods in Engineering ◽

10.1002/(sici)1097-0207(19961230)39:24<4159::aid-nme52>3.0.co;2-s ◽

1996 ◽

Vol 39 (24) ◽

pp. 4159-4182 ◽

Cited By ~ 11

Author(s):

J. PETERA ◽

V. NASSEHI

Keyword(s):

Finite Element ◽

Finite Element Model ◽

Shallow Water ◽

Shallow Water Equations ◽

Element Model ◽

Fluid Particle ◽

Two Dimensional ◽

Particle Trajectories ◽

Lagrangian Framework ◽

Dimensional Finite Element

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Three-Dimensional Response of the Supported-Deep Excavation System: Case Study of a Large Scale Underground Metro Station

Geosciences ◽

10.3390/geosciences10020076 ◽

2020 ◽

Vol 10 (2) ◽

pp. 76

Author(s):

Ashraf Hefny ◽

Mohamed Ezzat Al-Atroush ◽

Mai Abualkhair ◽

Mariam Juma Alnuaimi

Keyword(s):

Finite Element ◽

Finite Element Model ◽

Large Scale ◽

Three Dimensional ◽

Element Model ◽

Two Dimensional ◽

Deep Excavation ◽

Metro Station ◽

Dimensional Finite Element ◽

Three Dimensional Finite Element

The complexities and the economic computational infeasibility associated in some cases, with three-dimensional finite element models, has imposed a motive for many investigators to accept numerical modeling simplification solutions such as assuming two-dimensional (2D) plane strain conditions in simulation of several supported-deep excavation problems, especially for cases with a relatively high aspect ratio in plan dimensions. In this research, a two-dimensional finite element model was established to simulate the behavior of the supporting system of a large-scale deep excavation utilized in the construction of an underground metro station Rod El Farrag project (Egypt). The essential geotechnical engineering properties of soil layers were calculated using results of in-situ and laboratory tests and empirical correlations with SPT-N values. On the other hand, a three-dimensional finite element model was established with the same parameters adopted in the two-dimensional model. Sufficient sensitivity numerical analyses were performed to make the three-dimensional finite element model economically feasible. Results of the two-dimensional model were compared with those obtained from the field measurements and the three-dimensional numerical model. The comparison results showed that 3D high stiffening at the primary walls’ corners and also at the locations of cross walls has a significant effect on both the lateral wall deformations and the neighboring soil vertical settlement.

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