scholarly journals On conditions and parameters important to model sensitivity for unsaturated flow through layered, fractured tuff; Results of analyses for HYDROCOIN [Hydrologic Code Intercomparison Project] Level 3 Case 2: Yucca Mountain Project

1990 ◽  
Author(s):  
R.W. Prindle ◽  
P.L. Hopkins
Keyword(s):  
Unsaturated Flow ◽  
Yucca Mountain ◽  
Model Sensitivity ◽  
Level 3 ◽  
Intercomparison Project ◽  
Flow Through ◽  
Project Level

scholarly journals Sensitivity of mid-Pliocene climate to changes in orbital forcing, and PlioMIP's boundary conditions

2020 ◽  
Author(s):  
Eric Samakinwa ◽  
Christian Stepanek ◽  
Gerrit Lohmann
Keyword(s):  
Boundary Conditions ◽  
The Arctic ◽  
Seasonal Temperature ◽  
Model Output ◽  
Orbital Forcing ◽  
Model Intercomparison ◽  
Model Sensitivity ◽  
Modelling Methodology ◽  
Intercomparison Project ◽  
Two Phases

Abstract. In this study, we compare results obtained from modelling the mid-Pliocene warm period using the Community Earth System Models (COSMOS, version: COSMOS-landveg r2413, 2009) with the two different modelling methodologies and sets of boundary conditions prescribed for the two phases of the Pliocene Model Intercomparison Project (PlioMIP), tagged PlioMIP1 and PlioMIP2. Boundary conditions, model forcing, and modelling methodology for the two phases of PlioMIP differ considerably in palaeogeography, in particular with regards to the state of ocean gateways, ice-masks, treatment of vegetation and topography. Further differences between model setups as suggested for PlioMIP1 and PlioMIP2 consider updates to the concentration of trace gases: atmospheric carbon dioxide (CO2), is specified as 405 and 400 parts per million by volume (ppmv) for PlioMIP1 and PlioMIP2, respectively. There are also minor differences in the concentrations of methane (CH4) and nitrous oxide (N2O) due to changes in the protocol of the Paleoclimate Model Intercomparison Project (PMIP) from phase 3 to phase 4. Employing a single model across two phases of PlioMIP enables a better understanding of the impact that the various differences in modelling methodology between PlioMIP1 and PlioMIP2 have on model output. Yet, a dedicated comparison of COSMOS model output of PlioMIP1 and PlioMIP2 is not in the curriculum of model analyses proposed in PlioMIP2. Here, we bridge the gap between our contributions to PlioMIP1 (Stepanek and Lohmann, 2012) and PlioMIP2 (Stepanek et al., 2020). We highlight some of the effects that differences in the chosen mid-Pliocene model setup (PlioMIP2 vs. PlioMIP1) have on the climate state as derived with the COSMOS, as this information will be valuable in the framework of the model-model and model-data-comparison within PlioMIP2. We evaluate the model sensitivity to improved mid-Pliocene boundary conditions using PlioMIP's core mid-Pliocene experiments for PlioMIP1 and PlioMIP2, and present further simulations where we test model sensitivity to variations in palaeogeography, orbit and concentration of CO2. Firstly, we highlight major changes in boundary conditions from PlioMIP1 to PlioMIP2 and also the challenges recorded from the initial effort. The results derived from our simulations show that COSMOS simulates a mid-Pliocene climate state that is 0.29 K colder in PlioMIP2, if compared to PlioMIP1 (17.82 °C in PlioMIP1, 17.53 °C in PlioMIP2, values based on simulated surface skin temperature). On one hand, high-latitude warming, which is supported by proxy evidence of the mid-Pliocene, is underestimated in simulations of both PlioMIP1 and PlioMIP2. On the other hand, spatial variations in surface air temperature (SAT), sea surface temperature (SST) as well as the distribution of sea ice suggest improvement of simulated SAT and SST in PlioMIP2 if employing the updated palaeogeography. Our PlioMIP2 mid-Pliocene simulation produces warmer SSTs in the Arctic and North Atlantic Ocean than derived from the respective PlioMIP1 climate state. The difference in prescribed CO2 accounts for 1.1 K of warming in the Arctic, leading to an ice-free summer in the PlioMIP1 simulation, and a quasi ice-free summer in PlioMIP2. Beyond the official set of PlioMIP2 simulations, we present further simulations and analyses that sample the phase space of potential alternative orbital forcings that have acted during the Pliocene and may have impacted on geological records. Employing orbital forcing, which differ from that proposed for PlioMIP2 (i.e. corresponding to Pre-Industrial conditions) but falls into the Mid-Pliocene time period targeted in the PlioMIP, leads to pronounced annual and seasonal temperature variations, which are not directly retrievable from the marine and terrestrial reconstruction of the time-slice.

scholarly journals Experimental Study of Rainfall Infiltration in an Analog Fracture-matrix System

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Zhen Zhong ◽  
Huicai Gao ◽  
Yunjin Hu
Keyword(s):  
Unsaturated Flow ◽  
Rainfall Infiltration ◽  
Combination Method ◽  
Matrix System ◽  
Capillary Barrier ◽  
Hydraulic Behaviour ◽  
Experimental Apparatus ◽  
Matrix Interactions ◽  
The Matrix ◽  
Flow Through

In this study, an experimental apparatus was developed to investigate unsaturated infiltration in an analog fracture-matrix system. Fracture and adjacent matrix is simulated by sands with various particle sizes. Four rainfall infiltration experiments were performed on the analog fracture-matrix system at a constant rainfall rate of 100 mm/h. The process of rainfall infiltration is measured by a combination method of tensiometers and quick moisture apparatus. The measured results reveal that fracture-matrix interactions certainly exert influences on the hydraulic behaviour of unsaturated fractured matrix, and the fluid flow mainly infiltrates along the nonuniform paths within the matrix. Moreover, it is observed that the influences are greater when using a coarser sand to mimic the fracture. Specifically, the wetting phase in the matrix moves faster than that in the fracture; the fracture, therefore, acts as a vertical capillary barrier, but there exists lateral water exchange from the matrix to the fracture. Overall, this study has demonstrated the importance of fracture/matrix interactions, which should be considered when dealing with unsaturated flow through permeable matrices.

Permeability Modeling Considering Microstructure of Preform

2007 ◽  
Vol 334-335 ◽  
pp. 437-440 ◽  
Author(s):  
Do Hoon Lee ◽  
Joon Ho Lee ◽  
Woo I. Lee
Keyword(s):  
Porous Medium ◽  
Unsaturated Flow ◽  
Manufacturing Industries ◽  
Experimental Measurements ◽  
Resin Flow ◽  
Flow Conditions ◽  
Composite Manufacturing ◽  
Liquid Molding ◽  
Flow Through ◽  
Inhomogeneous Microstructure

Liquid molding processes are becoming more popular among the composite manufacturing industries due to their versatility and economy among other merits. In analyzing the flow during the process, permeability is the most important parameter. Permeability has been regarded as a property of the porous medium. However, in many practical cases, the value may vary depending on the flow conditions such as the flow rate. It is speculated that this deviation is caused by inhomogeneous microstructure of the medium. In this study, numerical simulations as well as experimental measurements have been done to investigate the cause of deviation. Microstructure of porous medium was modeled as an array of porous cylinders. Resin flow through the array was simulated numerically. Simulations were performed for two different flow conditions, namely saturated flow and unsaturated flow. Based upon the results, permeabilities were estimated and compared for the two flow conditions. In addition, a model was proposed to predict the permeability for different flow conditions. Results showed that experimental data were in agreement with the prediction by the model.

Unsaturated Flow through a Small Fracture-Matrix Network: Part 1. Experimental Observations

2004 ◽  
Vol 3 (1) ◽  
pp. 90-100 ◽  
Author(s):  
T. R. Wood ◽  
R. J. Glass ◽  
T. R. McJunkin ◽  
R. K. Podgorney ◽  
R. A. Laviolette ◽  
...  
Keyword(s):  
Unsaturated Flow ◽  
Flow Through

Modelling chemical and biological reactions during unsaturated flow through sandy soils

Soil Research ◽  
2010 ◽  
Vol 48 (3) ◽  
pp. 221
Author(s):  
B. Ludwig ◽  
S. Herrmann ◽  
K. Michel
Keyword(s):  
Ion Transport ◽  
Unsaturated Flow ◽  
Sandy Soils ◽  
Cation Transport ◽  
Anion Transport ◽  
Calibration Model ◽  
Model Variant ◽  
Reliable Assessment ◽  
Model Predictions ◽  
Flow Through

Predicting chemical and biological reactions during unsaturated flow through soils is complex, and the accuracy of model predictions is open to question. Objectives were to test how accurately the transport of nutrients (Ca2+, Mg2+, K+, NH4+, and NO3–) in soils can be predicted when differing amounts of nutrients or acid are added. Undisturbed columns of 2 sandy surface soils from arable sites in Darmstadt, Germany, and Sohar, Oman, were irrigated for 360 and 376 days with 3 mm/day at 10°C. Three treatments were carried out: the columns were irrigated with differing fertilising solutions (Fert-1 or Fert-2 treatments) or with HCl. The model PHREEQC2 was used to calculate 1-dimensional transport, inorganic complexation, dissolution or precipitation of CaCO3, multiple cation exchange, and nitrification. We compared 3 model variants: one with no adjustable parameters, a second with optimised nitrification rates and pCO2, and a third with an additional optimisation of the exchange coefficients. In model variant v2 and v3, the Fert-1 treatment was used for calibration. Model variant v1 was of little use in predicting cation transport in soils. The second was more appropriate for both soils, but an optimisation of the exchange coefficients (model variant v3) was required for a more accurate description (Fert-1) and prediction (Fert-2 and HCl) of ion transport. The included proton buffering reactions resulted in a moderately accurate prediction of pH and release of ions. Nitrification in the Fert-1 and Fert-2 experiments considered in the model variants accounted for a range of 0.03–0.04 µmol N/(day.g soil). Overall, our results indicate that calibration experiments are required for a reliable assessment of ion transport in soils during unsaturated flow. The parameter optimisation program PEST in combination with PHREEQC2 best simulated cation and anion transport in sandy soils under unsaturated conditions.

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