scholarly journals A 2-D and 3-D Composite Dimensional Fully Coupled Surface and Subsurface Flow Model

2012 ◽  
Vol 17 (2) ◽  
pp. 1-13 ◽  
Author(s):  
Natsuki Buma ◽  
Junichiro Takeuchi ◽  
Toshihiko Kawachi ◽  
Shunsuke Chono ◽  
Chie Imagawa ◽  
...  
Keyword(s):  
Flow Model ◽  
Subsurface Flow ◽  
Fully Coupled ◽  
Surface And Subsurface Flow

A scalable coupled surface–subsurface flow model

2015 ◽  
Vol 116 ◽  
pp. 74-87 ◽  
Author(s):  
T. De Maet ◽  
F. Cornaton ◽  
E. Hanert
Keyword(s):  
Flow Model ◽  
Subsurface Flow

scholarly journals Global Sensitivity Analysis and Adaptive Stochastic Sampling of a Subsurface-Flow Model Using Active Subspaces

2019 ◽  
Author(s):  
Daniel Erdal ◽  
Olaf A. Cirpka
Keyword(s):  
Sensitivity Analysis ◽  
Flow Model ◽  
Global Sensitivity Analysis ◽  
Subsurface Flow ◽  
Full Model ◽  
Stochastic Sampling ◽  
Global Sensitivity ◽  
Parameter Combination ◽  
Active Subspaces ◽  
Active Subspace

Abstract. Integrated hydrological modelling of domains with complex subsurface features requires many highly uncertain parameters. Performing a global uncertainty analysis using an ensemble of model runs can help bring clarity which of these parameters really influence system behavior, and for which high parameter uncertainty does not result in similarly high uncertainty of model predictions. However, already creating a sufficiently large ensemble of model simulation for the global sensitivity analysis can be challenging, as many combinations of model parameters can lead to unrealistic model behavior. In this work we use the method of active subspaces to perform a global sensitivity analysis. While building-up the ensemble, we use the already existing ensemble members to construct low-order meta-models based on the first two active subspace dimensions. The meta-models are used to pre-determine whether a random parameter combination in the stochastic sampling is likely to result in unrealistic behavior, so that such a parameter combination is excluded without running the computationally expensive full model. An important reason for choosing the active subspace method is that both the activity score of the global sensitivity analysis and the meta-models can easily be understood and visualized. We test the approach on a subsurface flow model including uncertain hydraulic parameter, uncertain boundary conditions, and uncertain geological structure. We show that sufficiently detailed active subspaces exist for most observations of interest. The pre-selection by the meta-model significantly reduces the number of full model runs that must be rejected due to unrealistic behavior. An essential but difficult part in active subspace sampling using complex models is approximating the gradient of the simulated observation with respect to all parameters. We show that this can effectively and meaningful be done with second-order polynomials.

scholarly journals Surface and subsurface contributions to the build-up of forces on bed particles

2018 ◽  
Vol 851 ◽  
pp. 558-572 ◽  
Author(s):  
Alessandro Leonardi ◽  
D. Pokrajac ◽  
F. Roman ◽  
F. Zanello ◽  
V. Armenio
Keyword(s):  
Mutual Influence ◽  
Subsurface Flow ◽  
Porous Wall ◽  
Industrial Applications ◽  
Solid Particles ◽  
Free Flow ◽  
Spherical Particles ◽  
Large Eddy ◽  
Lift Forces ◽  
Surface And Subsurface Flow

In nature and in many industrial applications, the boundary of a channel flow is made of solid particles which form a porous wall, so that there is a mutual influence between the free flow and the subsurface flow developing inside the pores. While the influence of the porous wall on the free flow has been well studied, less well characterized is the subsurface flow, due to the practical difficulties in gathering information in the small spaces given by the pores. It is also not clear whether the subsurface flow can host turbulent events able to contribute significantly to the build-up of forces on the particles, potentially leading to their dislodgement. Through large eddy simulations, we investigate the interface between a free flow and a bed composed of spherical particles in a cubic arrangement. The communication between surface and subsurface flow is in this case enhanced, with relatively strong turbulent events happening also inside the pores. After comparing the simulation results with a previous experimental work from a similar setting, the forces experienced by the boundary particles are analysed. While it remains true that the lift forces are largely dependent on the structure of the free flow, turbulence inside the pores can also give a significant contribution. Pressure inside the pores is weakly correlated to the pressure in the free flow, and strong peaks above and below a particle can happen independently. Ignoring the porous layer below the particle from the computations leads then in this case to an underestimation of the lift forces.

Sign in / Sign up

Export Citation Format

Share Document