scholarly journals Propagating ice front induces gas bursts and ultrasonic acoustic emissions from freezing xylem

2019 ◽  
Vol 40 (2) ◽  
pp. 170-182
Author(s):  
Anna Lintunen ◽  
Adriano Losso ◽  
Juho Aalto ◽  
Tommy Chan ◽  
Teemu Hölttä ◽  
...  
Keyword(s):  
Bubble Dynamics ◽  
Bubble Formation ◽  
Xylem Sap ◽  
Test Chamber ◽  
Acoustic Emissions ◽  
Ice Formation ◽  
Co2 Efflux ◽  
Salix Caprea ◽  
Complex Process ◽  
Ice Lattice

Abstract Ice formation and propagation in the xylem of plants is a complex process. During freezing of xylem sap, gases dissolved in liquid sap are forced out of the ice lattice due to their low solubility in ice, and supersaturation of xylem sap as well as low water potential (Ѱ) are induced at the ice–liquid interface. Supersaturation of gases near the ice front may lead to bubble formation and potentially to cavitation and/or to burst of gases driven out from the branch. In this study, we investigated the origin and dynamics of freezing-related gas bursts and ultrasonic acoustic emissions (AEs), which are suggested to indicate cavitation. Picea abies (L.) H. Karst. and Salix caprea L. branch segments were exposed to frost cycles in a temperature test chamber, and CO2 efflux (indicating gas bursts) and AEs were recorded. On freezing, two-thirds of the observed gas bursts originated from the xylem and only one-third from the bark. Simultaneously with gas bursts, AEs were detected. Branch Ѱ affected both gas bursts and AEs, with high gas burst in saturated and dry samples but relevant AEs only in the latter. Repeated frost cycles led to decreasing gas burst volumes and AE activity. Experiments revealed that the expanding ice front in freezing xylem was responsible for observed gas bursts and AEs, and that branch Ѱ influenced both processes. Results also indicated that gas bursts and cavitation are independently induced by ice formation, though both may be relevant for bubble dynamics during freezing.

Using Wavelet Analysis to Distinguish Cavitation Acoustic Emissions From Blunt Impact Noise

2021 ◽  
Author(s):  
Christopher Eckersley ◽  
Joost Op 't Eynde ◽  
Mitchell Abrams ◽  
Cameron R. Bass
Keyword(s):  
Wavelet Transform ◽  
High Speed ◽  
Acoustic Noise ◽  
Bubble Formation ◽  
Acoustic Emissions ◽  
Wide Band ◽  
Water Tank ◽  
Impact Noise ◽  
Blunt Impact

Abstract Cavitation has been shown to have implications for head injury, but currently there is no solution for detecting the formation of cavitation through the skull during blunt impact. The goal of this communication is to confirm the wideband acoustic wavelet signature of cavitation collapse, and determine that this signature can be differentiated from the noise of a blunt impact. A controlled, laser induced cavitation study was conducted in an isolated water tank to confirm the wide band acoustic signature of cavitation collapse in the absence of a blunt impact. A clear acrylic surrogate head was impacted to induce blunt impact cavitation. The bubble formation was imaged using a high speed camera, and the collapse was synched up with the wavelet transform of the acoustic emission. Wideband acoustic response is seen in wavelet transform of positive laser induced cavitation tests, but absent in laser induced negative controls. Clear acrylic surrogate tests showed the wideband acoustic wavelet signature of collapse can be differentiated from acoustic noise generated by a blunt impact. Broadband acoustic signal can be used as a biomarker to detect the incidence of cavitation through the skull as it consists of frequencies that are low enough to potentially pass through the skull but high enough to differentiate from blunt impact noise. This lays the foundation for a vital tool to conduct CSF cavitation research in-vivo.

Numerical Study of Bubble Growth on a Micro-Finned Surface

2011 ◽  
Author(s):  
Woorim Lee ◽  
Gihun Son
Keyword(s):  
Heat Transfer ◽  
Bubble Growth ◽  
Bubble Dynamics ◽  
Numerical Study ◽  
Removal Rate ◽  
Bubble Formation ◽  
Experimental Studies ◽  
Nucleate Boiling ◽  
Finned Surface ◽  
Fin Spacing

Bubble growth on a micro-finned surface, which can be used in enhancing boiling heat transfer, is numerically investigated by solving the conservation equations of mass, momentum, and energy. The bubble deformation or the liquid-vapor interface is determined by the sharp-interface level-set method, which is modified to include the effect of phase change and to treat the contact angle and the evaporative heat flux from the liquid microlayer on an immersed solid surface of a microfin. The numerical method is applied to clarify bubble growth and heat transfer characteristics on a surface including fin and cavity during nucleate boiling which have not been provided from the previous experimental studies. The effects of single fin, fin-cavity distance, and fin-fin spacing on the bubble dynamics are investigated. The micro-fin is found to affect the activation of cavity. The fin-cavity configuration is found to determine the bubble formation in a cavity. The vapor removal rate is also observed to significantly depend on the fin-fin spacing.

scholarly journals Comparison of CO<sub>2</sub> and O<sub>2</sub> fluxes demonstrate retention of respired CO<sub>2</sub> in tree stems from a range of tree species

2019 ◽  
Vol 16 (1) ◽  
pp. 177-191 ◽  
Author(s):  
Boaz Hilman ◽  
Jan Muhr ◽  
Susan E. Trumbore ◽  
Norbert Kunert ◽  
Mariah S. Carbone ◽  
...  
Keyword(s):  
Tree Species ◽  
Sap Flow ◽  
Xylem Sap ◽  
Co2 Efflux ◽  
Forest Trees ◽  
O2 Uptake ◽  
Stem Respiration ◽  
Low Solubility ◽  
Main Substrate

Abstract. The ratio of CO2 efflux to O2 influx (ARQ, apparent respiratory quotient) in tree stems is expected to be 1.0 for carbohydrates, the main substrate supporting stem respiration. In previous studies of stem fluxes, ARQ values below 1.0 were observed and hypothesized to indicate retention of respired carbon within the stem. Here, we demonstrate that stem ARQ < 1.0 values are common across 85 tropical, temperate, and Mediterranean forest trees from nine different species. Mean ARQ values per species per site ranged from 0.39 to 0.78, with an overall mean of 0.59. Assuming that O2 uptake provides a measure of in situ stem respiration (due to the low solubility of O2), the overall mean indicates that on average 41 % of CO2 respired in stems is not emitted from the local stem surface. The instantaneous ARQ did not vary with sap flow. ARQ values of incubated stem cores were similar to those measured in stem chambers on intact trees. We therefore conclude that dissolution of CO2 in the xylem sap and transport away from the site of respiration cannot explain the low ARQ values. We suggest refixation of respired CO2 in biosynthesis reactions as possible mechanism for low ARQ values.

scholarly journals Effects of xylem water transport on CO2 efflux of woody tissue in a tropical tree, Amazonas State, Brazil

Hoehnea ◽  
2012 ◽  
Vol 39 (1) ◽  
pp. 139-144 ◽  
Author(s):  
Norbert Kunert ◽  
Alida Mercado Cárdenas
Keyword(s):  
Xylem Sap ◽  
Major Influence ◽  
Tissue Respiration ◽  
Co2 Efflux ◽  
Diurnal Changes ◽  
Sap Flux ◽  
Woody Tissue ◽  
Night Time ◽  
Amazonas State ◽  
Xylem Sap Flux

We assessed the effect of xylem sap flux on radial CO2 efflux of woody tissue of a tropical trees species growing in the Center of Manaus (Amazonas State, Brazil). An open chamber system was used to constantly measure diurnal changes in CO2 efflux over several days. Xylem sap flux was monitored additionally. We found a strong relationship between temperature and woody tissue respiration rates during night time. CO2 efflux rates were reduced up to 35% during daytime most probably due to vertical water uptake within the tree trunks. The results suggest a distinct daytime depression of the CO2 efflux compared with a night time temperature relationship. Xylem sap flux appears to be a major influence on CO2 efflux rates. The reductions in CO2 efflux will become most distinct during periods with a high evaporative demand and predictions of CO2 efflux by the temperature/flux relation are critical during these periods.

A model for influence of exercise on formation and growth of tissue bubbles during altitude decompression

2000 ◽  
Vol 279 (6) ◽  
pp. R2304-R2316 ◽  
Author(s):  
Philip P. Foster ◽  
Alan H. Feiveson ◽  
Roland Glowinski ◽  
Michael Izygon ◽  
Aladin M. Boriek
Keyword(s):  
Bubble Dynamics ◽  
Bubble Formation ◽  
Surrounding Tissue ◽  
Pressure Gradients ◽  
Physiological Changes ◽  
In Series ◽  
Thermodynamic Forces ◽  
Exercise Induced ◽  
Response To Exercise ◽  
Tissue Motion

In response to exercise performed before or after altitude decompression, physiological changes are suspected to affect the formation and growth of decompression bubbles. We hypothesized that the work to change the size of a bubble is done by gas pressure gradients in a macro- and microsystem of thermodynamic forces and that the number of bubbles formed through time follows a Poisson process. We modeled the influence of tissue O2 consumption on bubble dynamics in the O2transport system in series against resistances, from the alveolus to the microsystem containing the bubble and its surrounding tissue shell. Realistic simulations of experimental decompression procedures typical of actual extravehicular activities were obtained. Results suggest that exercise-induced elevation of O2 consumption at altitude leads to bubble persistence in tissues. At the same time, exercise-enhanced perfusion leads to an overall suppression of bubble growth. The total volume of bubbles would be reduced unless increased tissue motion simultaneously raises the rate of bubble formation through cavitation processes, thus maintaining or increasing total bubble volume, despite the exercise.

scholarly journals Bubble Nucleation and Growth of Dissolved Gas in Solution Flowing across a Cavitating Nozzle

2015 ◽  
Vol 773-774 ◽  
pp. 304-308 ◽  
Author(s):  
Zhen Hong Ban ◽  
Kok Keong Lau ◽  
Mohd Sharif Azmi
Keyword(s):  
Bubble Dynamics ◽  
Bubbly Flow ◽  
Bubble Formation ◽  
Computational Modelling ◽  
Nucleation And Growth ◽  
Bubble Nucleation ◽  
Supersaturated Solution ◽  
Computational Domain ◽  
Dissolved Gas ◽  
Growth Phenomenon

Computational modelling of dissolved gas bubble formation and growth in supersaturated solution is essential for various engineering applications, including flash vaporisation of petroleum crude oil. The common mathematical modelling of bubbly flow only caters for single liquid and its vapour, which is known as cavitation. This work aims to simulate the bubble nucleation and growth of dissolved CO2 in water across a cavitating nozzle. The dynamics of bubble nucleation and growth phenomenon will be predicted based on the hydrodynamics in the computational domain. The complex interrelated bubble dynamics, mass transfer and hydrodynamics was coupled by using Computational Fluid Dynamics (CFD) and bubble nucleation and growth model. Generally, the bubbles nucleate at the throat of the nozzle and grow along with the flow. Therefore, only the region after the throat of the nozzle has bubbles. This approach is expected to be useful for various types of bubbly flow modelling in supersaturated condition.

Sound of Single Vapor Bubbles

2006 ◽  
Author(s):  
Ho Sung Lee ◽  
Danny M. Higgs
Keyword(s):  
Spherical Harmonics ◽  
Vapor Bubble ◽  
High Speed ◽  
Bubble Dynamics ◽  
Acoustic Emissions ◽  
Sound Intensity ◽  
Initial Growth ◽  
Surprising Result ◽  
Vapor Bubbles ◽  
Significant Information

The recent preliminary acoustic measurements of single vapor bubbles on a heated platinum wire, combined with high-speed digital photography, provided significant information for the vapor bubble dynamics such as growth, departure, collapse or coalescence with a previous bubble. Furthermore, under a given condition, the numerous consecutive single bubbles consistently showed almost identical waveforms, even at different times. This surprising result indicates that the phenomenon is not a chaotic process, but an orderly mathematical process. The deceleration of a growing bubble following the rapid initial growth was apparently detected by the acoustic emissions as a negative acoustic pressure. This is believed to be a new observation and not seen in gas bubbles. Some successive bubbles clearly underwent the spherical harmonics and compared well with a series of photographs. These results are in contrast with the previous indeterminate measurements on the sound intensity and frequency in boiling in the literature. The information for vapor bubble dynamics will be supplementary to the gas bubble dynamics such as cavitation, sonoluminescence, etc. Visual observations will be valuable for the mathematicians who study the spherical harmonics analytically. Also, the technique and information may be applicable to the fields of science and engineering associated with vapor bubbles motion including boiling.

Bubble Formation Modeling in Matrix-Assisted Pulsed-Laser Evaporation Direct Write

2008 ◽  
Author(s):  
Yafu Lin ◽  
Kevin Foy ◽  
Yong Huang ◽  
Douglas B. Chrisey
Keyword(s):  
Physical Mechanism ◽  
Bubble Diameter ◽  
Bubble Formation ◽  
Pulsed Laser ◽  
Laser Evaporation ◽  
Direct Write ◽  
Phase Explosion ◽  
Glycerol Water ◽  
Complex Process ◽  
Proposed Model

Matrix-assisted pulsed-laser evaporation direct write (MAPLE DW) is emerging as a promising direct-write technology for printing microelectronics as well as biological constructs. To widely employ this technology, understanding of its physical mechanism is of need. In this study, the bubble formation process in MAPLE DW of glycerol-water coating is modeled based on the nucleation-based phase explosion theory. Based on the proposed model, the bubble diameter after expansion and cooling and bubble pressure can be predicted. Although the prediction overall overestimates the bubble diameter during the MAPLE DW experiments, the proposed model is considered satisfactory in reasonably predicting the bubble diameter as a first step endeavor for this complex process. It is expected that the introduction of more accurate models for energy loss should further help improve the model prediction accuracy.

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