Influence Of Transpiration Research Articles

Numerical study of gas–surface interface effects due to transpiration in a hypersonic flow over a blunt body

This paper investigates the impact of transpiration on a hypersonic flow over a cylinder, considering different degrees of rarefaction. The study analyzes the interaction between freestream argon gas flow at Mach 5 and transpiring argon gas at the fluid–solid interface at a velocity of 10 m/s. Freestream Knudsen numbers considered are 0.002, 0.01, 0.05, and 0.25, spanning from a continuum to rarefied regime. Flow simulations utilize the open-source direct simulation Monte Carlo solver, Stochastic PArallel Rarefied-gas Time-accurate Analyzer. The influence of transpiration on flow and surface properties is examined by comparing non-transpiration and transpiration cases. At all regimes, transpiration increases the normal shock stand-off distance, while a comparison of flow properties along the stagnation line reveals a reduction in the velocity and an increase in the post-shock temperature with transpiration. Surface heat flux comparison indicates that transpiring gas reduces heat flux on the cylinder's upstream-facing front surface at all Knudsen numbers. However, at Kn∞ = 0.25, a shift occurs, and surface heat flux starts increasing locally from the top/bottom point on the cylinder surface through the rear face of the cylinder. Furthermore, a test for the validity of the continuum-based blowing correction correlation function reveals the failure of the empirical model, even in the continuum regime at Kn∞ = 0.002, casting doubt on its applicability to vehicles with curvilinear blunt-body shapes. Additionally, a sensitivity analysis demonstrates that transpiring gas with a number density an order of magnitude higher than the freestream reduces stagnation peak heat flux by nearly 30%, while transpiring gas with a temperature two times higher than the freestream shows a ∼13% reduction.

Ternary hybrid nanofluid flow caused by thermal radiation and mass transpiration in a porous stretching/shrinking sheet

In the current analysis, ternary hybrid nanofluid flow with heat transfer under the influence of transpiration and radiation is explored. Partial differential equations (PDEs) of the current work are mapped by using a similarity variable to convert into ordinary differential equations (ODEs) form. The volume fractions of the ternary hybrid nanofluid are used in the entire calculation to achieve better results. The exact investigation of the momentum equation produces the domain value. The impact of thermal radiation is considered under energy equation and solved analytically with solution domain to yield the temperature profile. Graphical representations can be used to evaluate the effects of the factors thermal radiation, heat source or sink, and porous media. The present work is taken into consideration for numerous industrial applications.

Inter-comparison of past and projected climatic trends in Puerto Rico: 1950–2100

Abstract Past and projected climatic trends in Puerto Rico in the period 1950–2100 are evaluated by detection of slope and fit in smoothed time series and by the mapping of local and regional trends using 5- to 50-km resolution products. New outcomes include second-order upward trends for evaporation and sea surface height. At a regional scale, Hadley Cell overturning is drying the mid-troposphere, inducing a northerly tendency for trade winds. The past rainfall trend (1950–2020) has increased ∼10% on the Atlantic-facing seaboard. Warming seas (+.02 °C/year) and rising vegetation fraction induce more evaporation that is deepening the moist boundary layer and sustaining thermal orographic precipitation over the island. Historical trends and model projections show a decrease in rainfall in spring and an increase in autumn, attributable to the retreat of the jet stream and the influence of transpiration, respectively. Outcomes reveal competition between small- and large-scale processes, and an island-wide water balance sustained by diurnal cycling. Adapting to the rising sea level makes pro-active coastal management a necessity. HIGHLIGHTS Past and future climate changes are similar. Dataset and model resolution of <50 km help to quantify climate change for small islands. New research suggests that second-order trends are replacing linear trends. Impacts due to sea level rise and coastal erosion require management.

The influence of transpiration on foliar accumulation of salt and nutrients under salinity in poplar (Populus × canescens).

Increasing salinity is one of the major drawbacks for plant growth. Besides the ion itself being toxic to plant cells, it greatly interferes with the supply of other macronutrients like potassium, calcium and magnesium. However, little is known about how sodium affects the translocation of these nutrients from the root to the shoot. The major driving force of this translocation process is thought to be the water flow through the xylem driven by transpiration. To dissect the effects of transpiration from those of salinity we compared salt stressed, ABA treated and combined salt- and ABA treated poplars with untreated controls. Salinity reduced the root content of major nutrients like K+, Ca2+ and Mg2+. Less Ca2+ and Mg2+ in the roots resulted in reduced leaf Ca2+ and leaf Mg2+ levels due to reduced stomatal conductance and reduced transpiration. Interestingly, leaf K+ levels were positively affected in leaves under salt stress although there was less K+ in the roots under salt. In response to ABA, transpiration was also decreased and Mg2+ and Ca2+ levels decreased comparably to the salt stress treatment, while K+ levels were not affected. Thus, our results suggest that loading and retention of leaf K+ is enhanced under salt stress compared to merely transpiration driven cation supply.

Influence of transpiration cooling on second-mode instabilities investigated on hypersonic, conical flows

In the present study, the influence of active cooling on hypersonic boundary-layer transition at different Mach numbers, from 7 up to 10, is investigated. The analyses are carried out on a $$7^\circ$$ half-angle, blunted cone with different nose radii and various gas injection mass flow rates. In all cases, low mass fluxes, which do not inducing visible shocks in the schlieren images, are applied. As injection gas nitrogen is used. At the considered free stream conditions, second modes are the dominant boundary-layer instabilities, which are consequently the focus of this study. The stability analyses are performed by means of the stability code NOLOT, NOnLOcal Transition analysis, of the German Aerospace Center (DLR). The influence of different mass injections on the frequencies and growth rates of the second modes is analyzed in detail. The effect on the transition onset locations is discussed. The numerical predictions are compared with experimental results. The experimental data referred to in the present study were obtained in the DLR High Enthalpy Shock Tunnel Gottingen.

Influence of Transpiration on Cadmium (Cd) and Lead (Pb) Uptake by Cabbage, Carrots and Lettuce from Irrigation Water in Ghana

Influence of Transpiration on Cadmium (Cd) and Lead (Pb) Uptake by Cabbage, Carrots and Lettuce from Irrigation Water in Ghana

Assessing environmental and physiological controls over water relations in a Scots pine (Pinus sylvestris L.) stand through analyses of stable isotope composition of water and organic matter

This study investigated the influence of meteorological, pedospheric and physiological factors on the water relations of Scots pine, as characterized by the origin of water taken up, by xylem transport as well as by carbon isotope discrimination (Delta13C) and oxygen isotope enrichment (Delta18O) of newly assimilated organic matter. For more than 1 year, we quantified delta2H and delta18O of potential water sources and xylem water as well as Delta13C and Delta18O in twig and trunk phloem organic matter biweekly, and related these values to continuously measured or modelled meteorological parameters, soil water content, stand transpiration (ST) and canopy stomatal conductance (G(s)). During the growing season, delta18O and delta2H of xylem water were generally in a range comparable to soil water from a depth of 2-20 cm. Long residence time of water in the tracheids uncoupled the isotopic signals of xylem and soil water in winter. Delta18O but not Delta13C in phloem organic matter was directly indicative of recent environmental conditions during the whole year. Delta18O could be described applying a model that included 18O fractionation associated with water exchange between leaf and atmosphere, and with the production of organic matter as well as the influence of transpiration. Phloem Delta13C was assumed to be concertedly influenced by G(s) and photosynthetically active radiation (PAR) (as a proxy for photosynthetic capacity). We conclude that isotope signatures can be used as effective tools (1) to characterize the seasonal dynamics in source and xylem water, and (2) to assess environmental effects on transpiration and G(s) of Scots pine, thus helping to understand and predict potential impacts of climate change on trees and forest ecosystems.

The role of epidermal turgor in stomatal interactions following a local perturbation in humidity

AbstractHumidity in a small area of a Vicia faba L. leaf was perturbed with a flow of dry air from an 80 µm (inside diameter) needle, while the remainder of the leaf was maintained at high and constant humidity. The influence of the needle flow on the humidity at the leaf surface was quantified by using a spatially explicit dewpoint hygrometer to observe condensation patterns. When the dry air from a needle was applied to the leaf, stomata within the influence of the needle opened within the first few minutes of the perturbation, and local epidermal turgor pressure declined within the same time frame. When the needle flow was removed from the leaf, these responses were reversed, but with more variable kinetics. Stomata and epidermal cells outside the influence of the needle flow, which were exposed to a constant and high humidity, showed similar, but smaller, responses when the needle flow was applied to the leaf. Since the opening of these stomata should have had only a small effect on transpiration (because of the high humidity), it is likely that the reduction in epidermal turgor was the cause (rather than the result) of the stomatal opening. The magnitude of the turgor response was only loosely related to the distance from the needle flow up to distances of almost 400 µm. The data support the idea that neighbouring stomata can interact through the influence of transpiration on epidermal turgor.

THE EFFECT OF TRANSPIRATION ON THE ACCUMULATION OF CARBOHYDRATES IN TOMATO FRUIT.

Previous studies suggest that transpiration from fruit surface drives the inflow of phloem sap into fruits. In those studies, the increment of the size of fruits was restricted mechanically to avoid the effects of changes in fruit size on the import of water. In this experiment, the influence of transpiration on the accumulation of carbohydrates was investigated in intact tomato fruits. Tomato fruits. 7 days after flowering, as attached to the plants were enclosed in the chamber of low humidity (LH) or high humidity (HH) and they were sampled 38 days after flowering. The enlargement of LH fruits was smaller than that of HH fruits. The accumulation of dry matter and total sugars on a fruit basis was lower in LH fruits than in HH fruits. There was no difference in the content of dry matter between LH and HH fruits. The concentration of total sugars of LH fruits was slightly lower than that of HH fruits. Lower accumulation of carbohydrates in LH fruits shows that transpiration flow of phloem sap is not the predominant factor that controls the inflow of photosynthetic assimilates in intact tomato fruit.

Developmental Change in Panicle Water Potential in Rice.

Rice panicles start to transpire just after heading. We can therefore expect that the water potential of panicles changes little prior to heading and varies in response to transpiration after heading. To test this hypothesis, we followed the ontogenetic change of plant water potential from the panicle initiation stage to maturity in a wetland rice cultivar, Koshihikari, grown in a submerged rice field. Diurnal changes were also studied on selected days. Leaves underwent a gradual decrease in midday water potential, which is associated with plant development. A similar trend was also found in panicles, except just before the exposure of panicles to the atomosphere when a sudden and brief increase in the panicle water potential was observed. Before heading, the water potential of panicles changed little diurnally, whereas it fluctuated markedly in concert with a change in potential evapotranspiration after heading. The water potential of panicles was consistantly higher throughout phenological development than that of leaves, except during the last stage of the grain-filling period. The results suggest that, before heading, the water potential of rice panicles appears to be coupled strongly with water flux for growth. After heading, the influence of transpiration becomes predominant. Superimposed on these is the increase in plant resistance to water transport that is associated with plant development.

The influence of transpiration on the equilibration of leaf water with atmospheric water vapour

Abstract. The authors examine the isotopic composition of leaf water, at natural abundance levels, as influenced by transpiration rate. The isotopic composition of water of wheat leaves (Triticum aestivum L. var. Aroona) was followed while their transpiration rate adjusted to ‘steady‐state’ environmental conditions. Leaf diffusive resistance was modified by short‐term salt treatment and by plant culture in either nutrient solution, free‐draining sand, or vermiculite. Resultant changes in 18O and 2H in leaf water are described and fitted to the model of Leaney et al. (1985). The treatments with lower transpiration rates were found to have a greater fraction of their leaf water equilibrated with water vapour in the atmosphere. Comparable results were obtained with both 18O and 2H, with some differences being interpreted in terms of turbulence in the vapour diffusion path. The fraction of the leaf water equilibrated with the atmosphere varied between leaves of different ages. However, this may have been due to their different positions in the canopy.

Abstracts of papers presented at the annual meeting of the Canadian Phytopathological Society University of British Columbia, Vancouver 14-17 August 1988

Abstracts of papers presented at the annual meeting of the Canadian Phytopathological Society University of British Columbia, Vancouver 14-17 August 1988

The influence of transpiration by emergent plants on the water balance in lakes

From measurements taken over a period of 3 years of the transpiration of the helophytes Phragmites australis (Cav.) Trin. ex Steud., Typha angustifolia L., T. latifolia L. and Schoenoplectus lacustris (L.) Palla, the transpiration coefficients have been calculated. The variability of transpiration coefficients is presented against the background of parallel microclimatic measurements. The water losses during transpiration are compared to those due to evaporation from the open water surface. The necessity of taking into consideration water loss during transpiration when calculating the water balance in lakes is pointed out.

A Method of Predicting the Behavior of a Turbulent Boundary Layer With Discrete Transpiration Jets

A method is proposed for predicting the behavior of a turbulent boundary layer with heat transfer under the influence of transpiration with discrete jets. The boundary layer is treated as a laterally averaged flow and the effects of nonuniformity are introduced through additional momentum and energy source terms in the equations of motion. These nonuniformity interaction terms are obtained using solutions of a set of ordinary differential equations governing the trajectory of jets. The effects of interaction between the jet and boundary layer turbulence structure are also treated. The predictions of the theory are shown to compare well with available discrete jet-boundary layer data.

The Influence of Transpiration upon the Photosynthesis in Several Crop Plants

Many investigations have been made on transpiration and photosynthesis of plants. However, the relationship between transpiration and photosynthesis has not been completely estabilished. The study reported here was planned to elucidate the effect of transpiration on the apparent photosynthesis and the relation of temperature and photosynthesis in several crops:sweet potato, rice, soybean and peanut. 1) Experiments were conducted outdoors under full sunlight using an apparatus which has a humidity-controlling system (Fig.1). In early growth stage, photosynthesis was not affected by restraint of the trans-piration caused by increasing humidity in the chamber, but in late growth stage a marked increase of photosynthetic rates occurred by restraining the transpiration (Figs.2-5). These results suggest that water supply from root to the photosynthetic organ turns insufficient in the late growth stage. 2) Fig.6 and Fig.7 indicate the relation of leaf temperature and photosynthesis in sweet potato and soybean plant at various growth stages. In early growth stage, apparent photosynthesis was insensible of high temperature from 30 to 40°C. In late growth stage, however, apparent photosynthetic rates showed a rapid decrease at high-temperature range. These phenomena were also recognized in other crops, e.g., rice and peanut. From results of the investigation for the stomatal opening and fluctuation of water level in sweet potato leaves under various temperature condition, it may be concluded that depression of photo-synthetic rate at high-temperature range was due to a deficit of water content and high stomatal resistance in leaf. 3) In the series of experiments as shown in Figs.2-5, water vapour transfer coefficient (D) was calculated for several crops from the equation presented in the note of Fig.9. There was a close relationship between the transpiration and the ‘D' value. The‘D' values, selected under approximately constant conditions with leaf temperature of 35°C and air volume passing through a chamber of 8-11 m3/hr, showed high correlations to photosynthetic rates in three crops except soybean plant (Fig.1O). The‘D' value is a reciprocal of diffusion resistance(r) which can be divided into two components: (i) resistance in external air during diffusion away from leaf(ra), and (ii) resistance through the stomata(rs). It is considered that the ‘D' mainly depends on 1/rs in the case of Fig.10. Accordingly, when photosynthetic rate is high at high leaf temperature, stomata are widely open. 4) Two factors, total sugar content in root and the ratio of root dry weight (R) to leaf area (F), must be concerned with the water supply from root to photosynthetic organ. Therefore, both factors, whose changes with time are shown in Fig.14, would be correlated to the‘D' values of each growth stage

ON THE INFLUENCE OF TRANSPIRATION ON THE DISTRIBUTION OF GROWTH IN THE AVENA MESOCOTYL

A study is made of the influence of transpiration on the distribution of growth in dark-grown Avena seedlings. It appears that an increase in transpiration will cause a change in the distribution of growth in the mesocotyl in the same sense as the change that is caused by a small amount of red light i.e. the part of the mesocotyl that grows is restricted to the more apical part.

Sprinkler irrigation on clay soils in southern Finland I. Sprinkler irrigation, its technique and effect on soil moisture

During the last three years, 1964—66, investigations on sprinkler irrigation of spring cereals have been carried out. The experimental fields were clay soils in Southern Finland. Neutral river and lake waters containing small amounts of soluble salts were applied in the nighttime. The application rate of the rotary sprinklers used was 2.5—4 mm per hour with the radius of 12±2 m. With this technique the experimental soils having poor structure endured the irrigation without any crust formation. It was found that the sprinklers equipped with two nozzles distributed the water more uniformly than those with one nozzle. With the former sprinklers a fairly good uniformity was attained: The amount of water usually varied between 25 and 35 mm with an average of 30 mm, except in a relatively small area nearest to the sprinklers which received too much water and in the area at the greatest distance from the sprinklers with less than the average amounts of water. The soil water conditions were followed by gypsum blocks inserted at different depths. In each experimental year, within 2—3 weeks from sprouting, the available water in the top soils decreased to 50 per cent of the total capacity. This dry condition existed for two months in the years 1964 and 1966 and for one month in 1965. During these dry periods the top soils were near the wilting point for a long time, and in 1966 the available water was wholly exhausted. The influence of transpiration was effective also in deeper layers. In 1966, the soil reached the wilting point also at the depth of 40 cm and stayed at this condition for about one month. The effect of a 30—37 mm irrigation on the soil moisture conditions lasted only for 1—2 weeks. Thus, the rate of evapotranspiration was as much as 4 mm per day. The plants consumed water simultaneously from the whole root zone, yet, most effectively from the surface layers. The top soil (20 cm in thickness) which had reached the wilting point was not completely moistened by the amounts of water applied. This indicates the high capacity of clay soils to store water. It is also noteworthy that a part of irrigation water percolated to 40 cm before the soil at the depths of 10 and 20 cm had time to get to the field capacity. In experimental years, to ensure favourable moisture conditions to spring cereals several high applications of water would have been needed. This proves that also during the short growing season in Finland a serious shortage of water may occur.

EXPERIMENTS ON THE RELATION BETWEEN WATER ABSORPTION AND MINERAL UPTAKE BY PLANT ROOTS

Maize plants in water cultures were submitted to conditions of high transpiration in the sun and low transpiration in the dark. Transpiration rates were determined together with those of ammonium, potassium, nitrate and phosphate absorption from solutions at pH 6 and 20° centigrade. No significant influence of transpiration on ion absorption was found. These results seem to be at variance with those obtained by Hylmo with peas and by Brouwer with broad beans. However, the ion concentrations used were considerably lower than those used by Hylmo and Brouwer. Moreover, the possibility is discussed that the concentration- and transpiration-dependent component of the ion absorption might be great in pea and broad bean and small in maize. The seeming contradiction would then be reduced to a quantitative difference. The authors are indebted to Mrs E. H. Gloor for her kind help in the correction of the manuscript.

WALLACE AND CLUM, “LEAF TEMPERATURES”: A CRITICAL ANALYSIS WITH ADDITIONAL DATA

WALLACE AND CLUM (1938) have recently published a paper on leaf temperatures in which they present many interpretations and conclusions which appear to me as incorrect and unsound. Since the writers have published other papers that are thoroughly sound and since many readers may read the summary only or may fail to recognize the fallacies in the interpretations given-for several of them are easily overlooked-and since several of these interpretations and conclusions directly contradict those I have reported, I feel rather obliged to write the present paper in order to clarify certain points relating to factors influencing the temperatures of especially the influence of transpiration and radiation. Wallace and his colleagues have devised ingenious equipment by which one can obtain continuous records of various conditions such as radiation intensities, temperature, etc., which can be recorded by electrometric methods. By the use of this equipment, Wallace and Clum have attempted to obtain continuous records of leaf and air temperatures as influenced by various factors. From records obtained in these experiments, they concluded, among other things, that transpiration commonly cools leaves by amounts ranging from 6? to 90C.; that there seems to be no doubt . . . . that transpiration is necessary at times to prevent leaves or leaf parts normal to the sun from being injured; that a leaf of Heliopsis in full sunlight normally wilts every day and that the greatest cooling of 7?C. below air coincides with the period of most severe wilting; that a leaf even if covered by vaseline may transpire rapidly enough to be cooled below air temperature by as much as 50C.; that 'at night leaves are seldom, if ever, below air temperature due to loss (by radiation) to the sky .; that vaselining failed to prevent transpiration in leaves, while waxing leaves with a mixture of beeswax and rosin prevented transpiration and that a leaf covered with this wax becomes heated to killing temperature in the sun solely because the wax prevents cooling by transpiration. An examination of the evidence and reasoning that has led to these conclusions, however, indicates that each of these conclusions as well as other conclusions of Wallace and Clum are entirely unjustified. One of the major sources of error in their work is that the thermopile which they assumed. was at air temperature was probably 20 to 70C. above air temperature at least a part of the time, and thus their comparisons between leaf and air temperatures at these times were incorrect. That the thermopile was at times not at air temperature is clearly indicated by several independent sets of their own data, as well as by evidence from other sources. For example, in