Bulletin of the American Physical Society
76th Annual Meeting of the Division of Fluid Dynamics
Sunday–Tuesday, November 19–21, 2023; Washington, DC
Session L14: Biofluids: Plant Biomechanics |
Hide Abstracts |
Chair: Frederick Gosselin, Polytechnique Montreal Room: 144AB |
Monday, November 20, 2023 8:00AM - 8:13AM |
L14.00001: Poroelastic model of long-distance signals in vascular plants Vesna Bacheva, Fulton E Rockwell, Margaret Frank, Abraham D Stroock Plants exhibit remarkable adaptability in response to various environmental factors. To maintain hydration in an unsaturated environment, plants hold water in a state of stress characterized by negative water potentials and local chemical and mechanical equilibrium with the tissue matrix. This state can be perturbed by both biotic (e.g., wounding by pests, infection) and abiotic (e.g., drought, heat) stresses. Evidence suggests that the propagation of such perturbations can mediate long-distance signaling that allows the plant to mount a systemic coordinated response. However, we currently lack a theoretical framework for the mechanical and convective processes associated with such propagation of signals. |
Monday, November 20, 2023 8:13AM - 8:26AM |
L14.00002: Dynamics of stomatal regulation: A systems-scale model for understanding coupling between active and passive mechanisms Sahil Desai, Piyush Jain, Sabyasachi Sen, Abraham D Stroock, RJ Twohey, Anthony J Studer Climate change, with heightened stresses like water scarcity and atmospheric dryness poses challenges to crop productivity and food security. Stomata, the pores defined by guard cells on leaf surfaces, play a vital role in controlling carbon and water vapor exchange. Stomatal regulation involves water movement in or out of guard cells, influenced by leaf tissue biomechanics and hydraulics. This movement occurs through two mechanisms: hydropassive (HP), driven by changes in guard cell turgor pressure, and hydroactive (HA), initiated by biochemical osmotic adjustments in guard cells. Current mechanistic models for stomatal regulation lack coupling between the HA and HP mechanisms. |
Monday, November 20, 2023 8:26AM - 8:39AM |
L14.00003: Dynamic Functionality of Drip Tips on Tropical Leaves Crystal R Fowler, Akihito Kiyama, Rehan Marshall, Daniele Cicuzza, Noel Michele Holbrook Tropical vegetation in areas with high humidity are characterized by leaves having elongated tips. When it rains, water droplets accumulate at and fall from the elongated leaf apex, giving rise to their name: drip tips. Whether drip tips enhance the efficiency of water shedding from leaves, however, is poorly known. The goal of this study is to investigate whether drip tips lead to greater water shedding from leaves in high humidity environments. We constructed model leaves with four different tip lengths and one without any tip length. Two high-speed cameras were used to capture simulated water drops on the model leaf surface to measure the vibrational frequency and amplitude when the water sheds from the drip tip. The volume and mass of the water droplets are recorded with the addition of a force sensor measurement and the deflection of the model leaf. The frequency, mass of the water, and deflection of the model leaf are analyzed with a simple cantilever beam model to investigate the biomechanics of the drip tip. In the absence of a drip tip, our model leaf commonly exhibits a freely singular droplet (dripping) characteristic. On the other hand, we observe a rapid water jet-like behavior in leaves with longer drip tip lengths. The dynamics, mechanical properties, and leaf tip length of the leaf model are compared to tropical plants that have drip tips in the forest understory of Brunei, on the island of Borneo. |
Monday, November 20, 2023 8:39AM - 8:52AM |
L14.00004: Simulating Soft Coral Vibrations with a Wake Oscillator Model and 3D-Printed Flexible Branching Structures Frederick P Gosselin, Alexandre Villié, Mauricio Vanzulli Pena, Jorge Pérez-Zerpa, Jérôme Vétel, Stéphane Étienne Soft corals sway with the low-frequency swell of surface waves, and vibrate at a high frequency due to vortex-induced vibrations. It is hypothesized that these high-frequency vibrations allow the soft-coral colony to intercept more food particles and thus improve its feeding. In this conference talk, we present a simulation workflow to couple a co-rotational beam finite element formulation with a wake-oscillator model and an empirical drag formulation. This workflow allows simulating the low frequency, large amplitude sway of the branched structure and its high frequency response to vortex-induced vibrations. To validate these simulations, we perform water tunnel experiments on 3D-printed idealized coral colony structures. Simulations and experiments are performed for ramified structures with different numbers of branches, and for incrementing reduced velocity. Whereas a cantilevered beam exhibits well-defined and spaced-out lock-in ranges where the frequencies of vibration and of vortex shedding coalesce, a ramified structure with more and more branches exhibits a more and more continuous lock-in over increasing reduced velocity. A ramified structure with many branches possesses natural frequencies close to one another. There is thus always a natural frequency close to the frequency of vortex shedding. Moreover, the natural frequencies of branched structures are unenvenly spaced. Single frequency, high amplitude response is observed when vortex shedding occurs in a region of low frequency density, and multimodal, low amplitude response is observed when it occurs in a dense frequency region. Flexibility allows the coral colony to lower the drag it faces under fluid flow. The vibrationnal response of the colony allows it to "sweep more water" and encounter more particles. Whereas a beam without branches can maximize this gain in the lock-in region of the second mode, a branched structure smooths out the capture gain over a larger reduced velocity range. The code developed in this work is integrated in the open source co-rotational finite element software ONSAS. |
Monday, November 20, 2023 8:52AM - 9:05AM |
L14.00005: Experiment Measurement of Cytoplasmic Streaming Velocity within a Single Plant Cell Young-Su Ko, Chaeyeong Seo, Soosik Bang, Keunhwan Park, Youngsuk Nam, Hyun-Ah Lee, Choongyeop Lee Cytoplasmic streaming, driven by myosin movement on actin filaments, is believed to play a major role in substance transportation and cell metabolism within plant cells. For example, it has been suggested that the cytoplasmic streaming velocity has a correlation with a plant growth rate, such that a faster streaming velocity leads to a larger plant growth. However, this observation has been made only in Arabidopsis and has not been generalized to other plant species. In this study, we measure cytoplasmic streaming velocity by tracking the movement of vesicles along actin filaments in various plant species and phenotypes with different growth rates and growth heights to confirm the correlation between a plant growth and a streaming velocity. Furthermore, we study how the environmental conditions such as temperature and salinity affect the cytoplasmic streaming, while correcting the influence of viscosity change with the temperature based on an in-situ micro-rheology technique. We hope that our results may serve as a cornerstone for future studies to assess the environmental resistance of genetically modified plants at the cellular level. |
Monday, November 20, 2023 9:05AM - 9:18AM |
L14.00006: A network model of water and sugar transport coupling in leaves Melissa H Mai, Peter A.R. Bork, Chen Gao, Noel Michele Holbrook, Alexander Schulz, Tomas Bohr For every molecule of carbon dioxide a plant acquires for photosynthesis, hundreds of molecules of water are lost to the atmosphere. Yet, there is still uncertainty whether the movement of water between the vascular system and the sites of evaporation within the leaf occurs primarily through the cells or through the extracellular space. At the same time, sugars produced by photosynthesis must travel in the opposite direction of net water flow to be loaded into the vasculature and exported to the rest of the plant. To accomplish this, sugar transport must diffuse counter to advection that is generated by large negative water pressures. Here we present a network-based mathematical model accounting for pressure- and osmotically-driven flows to reconcile the two-way traffic of water and sugar in the leaf. In particular, we examine the parameter space in which the water and sugar currents move in opposite directions through the same physical channels. Furthermore, our model is generalizable to diverse anatomical configurations across plant genera, allowing us to also examine the physiology of the enigmatic, extravascular "transfusion tissue" characteristic of conifer needles. |
Monday, November 20, 2023 9:18AM - 9:31AM |
L14.00007: Effects of wave-driven plant reconfiguration on light availability to seagrass Tracy L Mandel Seagrasses are considered foundation species in marine and estuarine ecosystems by contributing biomass, habitat, and damping waves and currents. Globally, seagrass health and primary productivity are particularly threatened by factors that affect light availability, such as shading by algae, self-shading, and increased water column turbidity. This study focuses on how plant motion and reconfiguration lead to shading of an individual plant and its neighbors, and how wave/flow conditions, plant flexibility, and plant density affect light availability along a seagrass blade. We use a simple ray-optics shading model with the numerical model developed by Luhar and Nepf (2016) for a flexible blade under wavy flow to understand how phase-resolved plant behavior affects light availability as a function of vertical location in the water column. The results help us understand whether certain flow events or plant properties lead to increased shading, and what conditions are optimal for maximizing the light exposure to seagrass' photosynthetic tissue. |
Monday, November 20, 2023 9:31AM - 9:44AM |
L14.00008: Discovery of a new active matter process that controls plant-atmosphere coupling Sabyasachi Sen, Piyush Jain, Fulton E Rockwell, Robert J Twohey III, Matthew J Runyon, Anthony J Studer, Noel Michele Holbrook, Abraham D Stroock The leaves of plants dominate the exchange of water and carbon dioxide with the atmosphere over land. Their ability to regulate this exchange defines their productivity and resilience. To date, physiologists have recognized only a single point of control of this exchange, namely, via the opening and closing of stomata in the epidermis. Here, I will describe experiments with a new fluorescent nanoreporter of chemical potential of water that has allowed us to interrogate the constitutive properties relative to water transfer of the leaf mesophyll, the tissue that carries water from the xylem vessels to the sites of evaporation beneath the stomates. I will present: i) our discovery that this living tissue undergoes a massive loss of conductivity to water that leads to significant undersaturation inside the leaf, ii) the manner in which this process serves as a previously unrecognized point of control for water evaporation (transpiration), and iii) a model of multiphase transport processes in the mesophyll that guides our interpretation of our observations. I will show that the conductance of mesophyll tissue to water is under active biological regulation: a phenomenon that is captured by a pseudo 1-D representation of mass transfer with a single non-dimensional number describing the onset of extreme loss of hydraulic conductivity and emergence of non-stomatal control of transpiration. |
Monday, November 20, 2023 9:44AM - 9:57AM |
L14.00009: Investigation of flow structure through Asteraceae seed head Jena Shields, Chris Roh Dandelion (Taraxacum officinale) and salsify (Tragopogon dubius) are two species in the Asteraceae plant family that produce seed heads composed of wind dispersed seeds. For these seeds to be dispersed, they must first be released, or abscised, from the seed head. Previous studies have looked at the effects of wind speed, wind direction, temperature, turbulence, and humidity on seed abscission. Other studies have explored the flow structure through the pappus of dandelion seeds post-abscission. In this study, we explored the flow structure through the seed head pre-abscission using the smoke-wire visualization technique. Our results show that these seed heads act as rough, semi-porous, deformable spheres. We then compared these flow structures to that of flows around model spheres to investigate the effects of porosity and roughness. |
Monday, November 20, 2023 9:57AM - 10:10AM |
L14.00010: Molecular mechanisms of surfactant-enhanced transport of agrochemicals across the cuticular interface Chunzhi Wu, Gerald J Wang Surfactants and other adjuvants play a crucial role in improving the penetration of active ingredients through the transport-limiting barrier of the plant cuticle surface. However, the molecular mechanisms underpinning this process remain unclear. In this talk, we discuss work studying the interactions between a model plant cuticular membrane and surfactants using molecular-dynamics (MD) simulations, with a focus on diffusion within the waxy phase. To overcome the formidable computational challenges associated with MD simulations of rare events, we employ weighted-ensemble strategies to determine quantities of interest including rate constants, first-hit time, and free-energy profiles as a function of surfactant concentration. |
Monday, November 20, 2023 10:10AM - 10:23AM |
L14.00011: Poro-elastic bending of cellulose sponges: Inspired by curling leaves Jisoo Yuk, Andy Park, Sunghwan Jung Structural changes in plant leaves are a major indicator of the state of plants. Under high heat stress or insufficient water supply conditions, the leaves tend to curl to reduce water loss through transpiration and evaporation. However, the underlying mechanical reasons for leaf curling are unclear. Here, we study changes in out-of-plane curvature in leaf-inspired sponges, regarding the difference in contractility and rigidity of materials. In general, different types of plant cells with varying stiffness are distributed inside the leaf: soft parenchyma cells in the upper surface and middle region, and rigid veins with lignified sclerenchyma cells at the lower part. Inspired by this feature, we built a sponge with a polycarbonate sheet attached to its lower surface to introduce a difference in stiffness. When this sponge is soaked in water and allowed to dry naturally, its moisture content decreases, resulting in the edges contracting and the curvature increasing. This phenomenon is theoretically interpreted using the diffusion equation, which accounts for the change in water distribution caused by evaporation, as well as the changes in strain, force, and moment resulting from water loss-induced contraction. The relationship between moisture content and curvature can be explained by balancing structural stresses by curvature with local stresses induced by water evaporation. This result holds significant potential for smart materials or soft robotics related to moisture-induced shrinkage. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700