tfix post - adamsgaard.dk - my academic webpage | |
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Author: Anders Damsgaard <[email protected]> | |
Date: Thu, 16 Dec 2021 11:56:24 +0100 | |
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+<p>Today, <a href="mailto:[email protected]">Indraneel | |
+Kasmalkar</a> had his paper published in <a | |
+href="https://agupubs.onlinelibrary.wiley.com/journal/19422466">Journal of | |
+Geophysical Research: Earth Surface</a>. Congratulations Neel! He used | |
+my software <a href="https://src.adamsgaard.dk/sphere">sphere</a>, and | |
+sheared a granular assembledge with a non-trivial forcing in order to | |
+learn more about subglacial sediment behavior.</p> | |
+ | |
+ | |
+ | |
+<h2>Abstract</h2> | |
+<blockquote> | |
+<b>Shear Variation at the Ice-Till Interface Changes the Spatial | |
+Distribution of Till Porosity and Meltwater Drainage</b> | |
+<br><br> | |
+Indraneel Kasmalkar(1), Anders Damsgaard(2), Liran Goren(3), Jenny Suckale(1,4… | |
+<br><br> | |
+1: Department of Computational and Mathematical Engineering, Stanford Universi… | |
+<br> | |
+2: Department of Geoscience, Aarhus University, Denmark | |
+<br> | |
+3: Department of Earth and Environmental Sciences, Ben-Gurion University of th… | |
+<br> | |
+4: Department of Geophysics, Stanford University, CA, USA | |
+<br> | |
+5: Department of Civil and Environmental Engineering, Stanford University, CA,… | |
+<br><br> | |
+Plain-language summary:<br> | |
+The ice at the base of certain glaciers moves over soft sediments | |
+that route meltwater through the pore spaces in between the sediment | |
+grains. The ice shears the sediment, but it is not clear if this slow | |
+shearing is capable of changing the structure or volume of the pore space, | |
+or the path of the meltwater that flows through the sediment. To study | |
+the relations between the shearing of the sediment and the changes in its | |
+pore space, we use computer simulations that portray the sediment as a | |
+collection of closely packed spherical grains, where the pores are filled | |
+with meltwater. To shear the simulated sediment, the grains at the top | |
+are pushed with fixed speeds in the horizontal direction. Despite the | |
+slow shear, which is generally thought of as having no effect on pore | |
+space, our results show that shearing changes the sizes of the pores | |
+in between the grains, where large pores are formed near the top of the | |
+sediment layer. If the grains at the top are pushed with uneven speeds, | |
+then the largest pores are formed in the areas where grain speeds vary | |
+the most. We show that the exchange of meltwater between neighboring | |
+pores is faster than the movement of the grains, indicating that the | |
+meltwater can adjust quickly to changing pore space. | |
+<br><br> | |
+Abstract:<br> | |
+Many subglacial environments consist of a fine-grained, deformable | |
+sediment bed, known as till, hosting an active hydrological system that | |
+routes meltwater. Observations show that the till undergoes substantial | |
+shear deformation as a result of the motion of the overlying ice. The | |
+deformation of the till, coupled with the dynamics of the hydrological | |
+system, is further affected by the substantial strain rate variability | |
+in subglacial conditions resulting from spatial heterogeneity at the | |
+bed. However, it is not clear if the relatively low magnitudes of strain | |
+rates affect the bed structure or its hydrology. We study how laterally | |
+varying shear along the ice-bed interface alters sediment porosity and | |
+affects the flux of meltwater through the pore spaces. We use a discrete | |
+element model consisting of a collection of spherical, elasto-frictional | |
+grains with water-saturated pore spaces to simulate the deformation | |
+of the granular bed. Our results show that a deforming granular layer | |
+exhibits substantial spatial variability in porosity in the pseudo-static | |
+shear regime, where shear strain rates are relatively low. In particular, | |
+laterally varying shear at the shearing interface creates a narrow zone | |
+of elevated porosity which has increased susceptibility to plastic | |
+failure. Despite the changes in porosity, our analysis suggests that | |
+the pore pressure equilibrates near-instantaneously relative to the | |
+deformation at critical state, inhibiting potential strain rate dependence | |
+of the deformation caused by bed hardening or weakening resulting from | |
+pore pressure changes. We relate shear variation to porosity evolution | |
+and drainage element formation in actively deforming subglacial tills. | |
+</blockquote> | |
+ | |
+<h2>Links and references:</h2> | |
+<ul> | |
+ <li><a href="https://doi.org/10.1029/2021JF006460">Publication on jour… | |
+ <li><a href="papers/Kasmalkar et al 2021 Shear variation at the ice-ti… | |
+ <li><a href="https://src.adamsgaard.dk/sphere">Simulation software</a>… | |
+</ul> | |
diff --git a/pages/013-neel.txt b/pages/013-neel.txt | |
t@@ -0,0 +1,83 @@ | |
+Today, [1]Indraneel Kasmalkar had his paper published in [2]Journal of | |
+Geophysical Research: Earth Surface. Congratulations Neel! He used my software | |
+[3]sphere, and sheared a granular assembledge with a non-trivial forcing in | |
+order to learn more about subglacial sediment behavior. | |
+ | |
+Abstract | |
+ | |
+ Shear Variation at the Ice-Till Interface Changes the Spatial Distribution | |
+ of Till Porosity and Meltwater Drainage | |
+ | |
+ Indraneel Kasmalkar(1), Anders Damsgaard(2), Liran Goren(3), Jenny Suckale | |
+ (1,4,5) | |
+ | |
+ 1: Department of Computational and Mathematical Engineering, Stanford | |
+ University, CA, USA | |
+ 2: Department of Geoscience, Aarhus University, Denmark | |
+ 3: Department of Earth and Environmental Sciences, Ben-Gurion University of | |
+ the Negev, Beer-Sheva, Israel | |
+ 4: Department of Geophysics, Stanford University, CA, USA | |
+ 5: Department of Civil and Environmental Engineering, Stanford University, | |
+ CA, USA | |
+ | |
+ Plain-language summary: | |
+ The ice at the base of certain glaciers moves over soft sediments that | |
+ route meltwater through the pore spaces in between the sediment grains. The | |
+ ice shears the sediment, but it is not clear if this slow shearing is | |
+ capable of changing the structure or volume of the pore space, or the path | |
+ of the meltwater that flows through the sediment. To study the relations | |
+ between the shearing of the sediment and the changes in its pore space, we | |
+ use computer simulations that portray the sediment as a collection of | |
+ closely packed spherical grains, where the pores are filled with meltwater. | |
+ To shear the simulated sediment, the grains at the top are pushed with | |
+ fixed speeds in the horizontal direction. Despite the slow shear, which is | |
+ generally thought of as having no effect on pore space, our results show | |
+ that shearing changes the sizes of the pores in between the grains, where | |
+ large pores are formed near the top of the sediment layer. If the grains at | |
+ the top are pushed with uneven speeds, then the largest pores are formed in | |
+ the areas where grain speeds vary the most. We show that the exchange of | |
+ meltwater between neighboring pores is faster than the movement of the | |
+ grains, indicating that the meltwater can adjust quickly to changing pore | |
+ space. | |
+ | |
+ Abstract: | |
+ Many subglacial environments consist of a fine-grained, deformable sediment | |
+ bed, known as till, hosting an active hydrological system that routes | |
+ meltwater. Observations show that the till undergoes substantial shear | |
+ deformation as a result of the motion of the overlying ice. The deformation | |
+ of the till, coupled with the dynamics of the hydrological system, is | |
+ further affected by the substantial strain rate variability in subglacial | |
+ conditions resulting from spatial heterogeneity at the bed. However, it is | |
+ not clear if the relatively low magnitudes of strain rates affect the bed | |
+ structure or its hydrology. We study how laterally varying shear along the | |
+ ice-bed interface alters sediment porosity and affects the flux of | |
+ meltwater through the pore spaces. We use a discrete element model | |
+ consisting of a collection of spherical, elasto-frictional grains with | |
+ water-saturated pore spaces to simulate the deformation of the granular | |
+ bed. Our results show that a deforming granular layer exhibits substantial | |
+ spatial variability in porosity in the pseudo-static shear regime, where | |
+ shear strain rates are relatively low. In particular, laterally varying | |
+ shear at the shearing interface creates a narrow zone of elevated porosity | |
+ which has increased susceptibility to plastic failure. Despite the changes | |
+ in porosity, our analysis suggests that the pore pressure equilibrates | |
+ near-instantaneously relative to the deformation at critical state, | |
+ inhibiting potential strain rate dependence of the deformation caused by | |
+ bed hardening or weakening resulting from pore pressure changes. We relate | |
+ shear variation to porosity evolution and drainage element formation in | |
+ actively deforming subglacial tills. | |
+ | |
+Links and references: | |
+ | |
+ • [4]Publication on journal webpage (closed access) | |
+ • [5]Preprint PDF | |
+ • [6]Simulation software | |
+ | |
+ | |
+References: | |
+ | |
+[1] mailto:[email protected] | |
+[2] https://agupubs.onlinelibrary.wiley.com/journal/19422466 | |
+[3] https://src.adamsgaard.dk/sphere | |
+[4] https://doi.org/10.1029/2021JF006460 | |
+[5] https://adamsgaard.dk/papers/Kasmalkar%20et%20al%202021%20Shear%20variatio… | |
+[6] https://src.adamsgaard.dk/sphere |