Theory of Linear Poroelasticity with Applications to Geomechanics and Hydrogeology

Wang, Herbert F.

doi:10.1515/9781400885688

Cited by 821 publications

(1,427 citation statements)

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“…Order-of-magnitude calculations based on estimated pore sizes suggest that if the worm were a simple cylindrical biopolymeric hydrogel, hydrostatic pressure would equilibrate over the relatively slow timescales of the experiment (see the Supporting Material); this corresponds to the so-called drained limit in the literature on poroelasticity, and is consistent with the rate-independence of the data (Fig. 4) (40,41). But, if the pressure inside the worm were to equal that on the outside, why should the worm deform at all?…”

Section: Using Hydrostatic Pressure To Probe C Elegans Mechanicssupporting

confidence: 80%

“…4 B). The independence of the modulus from the stress rate over the experimentally accessible timescales suggests that the transport of water within the worm's body (and thus equilibration of pressure) is not a limiting factor in the deformation; this is consistent with calculations of the expected timescale for poroelastic effects, t~10 À2 s, suggesting that any hydrodynamic draining occurs very quickly (see the Supporting Material) (40,41).…”

Section: Worms Expand Under Negative Applied Pressuresupporting

confidence: 74%

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Worms under Pressure: Bulk Mechanical Properties of C. elegans Are Independent of the Cuticle

Gilpin

Uppaluri

Brangwynne

2015

Biophysical Journal

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The mechanical properties of cells and tissues play a well-known role in physiology and disease. The model organism Caenorhabditis elegans exhibits mechanical properties that are still poorly understood, but are thought to be dominated by its collagen-rich outer cuticle. To our knowledge, we use a novel microfluidic technique to reveal that the worm responds linearly to low applied hydrostatic stress, exhibiting a volumetric compression with a bulk modulus, k ¼ 140 5 20 kPa; applying negative pressures leads to volumetric expansion of the worm, with a similar bulk modulus. Surprisingly, however, we find that a variety of collagen mutants and pharmacological perturbations targeting the cuticle do not impact the bulk modulus. Moreover, the worm exhibits dramatic stiffening at higher stresses-behavior that is also independent of the cuticle. The stress-strain curves for all conditions can be scaled onto a master equation, suggesting that C. elegans exhibits a universal elastic response dominated by the mechanics of pressurized internal organs.

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Section: Using Hydrostatic Pressure To Probe C Elegans Mechanicssupporting

confidence: 80%

Section: Worms Expand Under Negative Applied Pressuresupporting

confidence: 74%

Worms under Pressure: Bulk Mechanical Properties of C. elegans Are Independent of the Cuticle

Gilpin

Uppaluri

Brangwynne

2015

Biophysical Journal

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“…After the plunger is depressed rapidly, the pressure rises rapidly to a high value at the closest gauge but is barely felt further away. Eventually, as water exits the system and progressively more of the load is born by the gel, the pressure at all positions reaches the same value, and the gel relaxes until it reaches an equilibrium where the applied load is everywhere balanced by the elastic stresses in the network [14]. This thought experiment and its variants have been well studied in simple physical gels [15,16], as well as in biogels such as cartilage and collagen networks [11,17].…”

Section: A Minimal Microstructural Model For Cytoplasm: Poroelasticitymentioning

confidence: 96%

Implications of a poroelastic cytoplasm for the dynamics of animal cell shape

Mitchison

Charras

Mahadevan

2008

Seminars in Cell & Developmental Biology

143

113

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Two views have dominated recent discussions of the physical basis of cell shape change during migration and division of animal cells: the cytoplasm can be modeled as a viscoelastic continuum, and the forces that change its shape are generated only by actin polymerization and actomyosin contractility in the cell cortex. Here, we question both views: we suggest that the cytoplasm is better described as poroelastic, and that hydrodynamic forces may be generally important for its shape dynamics. In the poroelastic view, the cytoplasm consists of a porous, elastic solid (cytoskeleton, organelles, ribosomes) penetrated by an interstitial fluid (cytosol) that moves through the pores in response to pressure gradients. If the pore size is small (30-60nm), as has been observed in some cells, pressure does not globally equilibrate on time and length scales relevant to cell motility. Pressure differences across the plasma membrane drive blebbing, and potentially other type of protrusive motility. In the poroelastic view, these pressures can be higher in one part of a cell than another, and can thus cause local shape change. Local pressure transients could be generated by actomyosin contractility, or by local activation of osmogenic ion transporters in the plasma membrane. We propose that local activation of Na+/H+ antiporters (NHE1) at the front of migrating cells promotes local swelling there to help drive protrusive motility, acting in combination with actin polymerization. Local shrinking at the equator of dividing cells may similarly help drive invagination during cytokinesis, acting in combination with actomyosin contractility. Testing these hypotheses is not easy, as water is a difficult analyte to track, and will require a joint effort of the cytoskeleton and ion physiology communities.

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“…4, the phase lead of water level relative to Earth tides is observable directly in the raw data and not due to cycle skipping. The apparent lack of causality (phase lead) is a result of translating the solution of a diffusion equation in terms of mass increment to a resultant pore pressure (Wang, 2000, Section 6.9). As pointed out by Roeloffs (1996), all aquifers respond as confined systems to very short-period disturbances, and drain to the water table in response to sufficiently long-period disturbances.…”

Section: Permeability Enhancement In the Nearfieldmentioning

confidence: 99%

Tidal response variation and recovery following the Wenchuan earthquake from water level data of multiple wells in the nearfield

Lai

Xue

et al. 2014

Tectonophysics

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An important dataset to emerge from the Wenchuan earthquake Fault Scientific Drilling project is direct measurement of the permeability evolution of a fault zone. In order to provide context for this new observation, we examined the evolution of tidal responses in the nearfield region (within~1.5 fault lengths) at the time of the mainshock. Previous work has shown that seismic waves can increase permeability in the farfield, but their effects in the nearfield are more difficult to discern. Close to an earthquake, hydrogeological responses are generally a combination of static and dynamic stresses. In this work, we examine the well water level data in the region of the large M w 7.9 Wenchuan earthquake and use the phase shift of tidal responses as a proxy for the permeability variations over time. We then compare the results with the coseismic water level pattern in order to separate out the dynamic and static effects. The coseismic water level pattern for observed steps coincident with the Wenchuan mainshock mainly tracks the expected static stress field. However, most of the wells that have resolvable tidal responses show permeability enhancement after this large earthquake regardless of whether the coseismic response for the well water level is increasing or decreasing, indicating permeability enhancement is a distinct process from static poroelastic strain.

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Theory of Linear Poroelasticity with Applications to Geomechanics and Hydrogeology

Cited by 821 publications

References 0 publications

Worms under Pressure: Bulk Mechanical Properties of C. elegans Are Independent of the Cuticle

Worms under Pressure: Bulk Mechanical Properties of C. elegans Are Independent of the Cuticle

Implications of a poroelastic cytoplasm for the dynamics of animal cell shape

Tidal response variation and recovery following the Wenchuan earthquake from water level data of multiple wells in the nearfield

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