2,674 research outputs found
Morphological and dynamic perturbations of autorotating samaras
No full textSamaras, the winged seeds of trees such as maple, ash, and poplar, utilize passive aerodynamic mechanisms for wind-driven dispersal. While maple samaras are well-documented for their stable autorotation, rolling samaras, including those from ash and poplar species, exhibit a coupled rolling-autorotative motion that remains less understood. The aerodynamic mechanisms governing both maple and rolling samaras are characterized, with a particular focus on their response to morphological and dynamic perturbations. High-speed imaging, wind tunnel experiments, and computational modeling quantify the kinematics, aerodynamic stability, and recovery mechanisms of samaras under controlled conditions. The influence of mass distribution, wing morphology, and environmental perturbations—such as crosswinds and raindrop impacts—on dispersal efficiency is analyzed. Experimental results demonstrate that maple samaras maintain robust autorotation despite external disturbances, rapidly recovering from transient aerodynamic disruptions. In contrast, rolling samaras exhibit a more complex aerodynamic response, where rolling motion influences both stability and lateral displacement in turbulent environments. Bridging gaps in the understanding of natural dispersal mechanisms advances ecological studies of wind-dispersed seeds and informs bio-inspired flight applications, particularly in passive aerial vehicle design. Insights from this work contribute to improving seed dispersal models, optimizing conservation strategies, and inspiring innovations in bio-inspired robotics and micro-airborne systems
Wind Dispersal of Natural and Biomimetic Maple Samaras
No full textMaple trees (genus Acer) accomplish the task of distributing objects to a wide area by producing seeds, known as samaras, which are carried by the wind as they autorotate and slowly descend to the ground. With the goal of supporting engineering applications, such as gathering environmental data over a broad area, we developed 3D-printed artificial samaras. Here, we compare the behavior of both natural and artificial samaras in both still-air laboratory experiments and wind dispersal experiments in the field. We show that the artificial samaras are able to replicate (within one standard deviation) the behavior of natural samaras in a lab setting. We further use the notion of windage to compare dispersal behavior, and show that the natural samara has the highest mean windage, corresponding to the longest flights during both high wind and low wind experimental trials. This study demonstrated a bioinspired design for the dispersed deployment of sensors and provides a better understanding of wind-dispersal of both natural and artificial samaras
Maple samaras recover autorotation following raindrop collisions.
No full textSamaras are known for their elegant and robust autorotation, a resilience that persists in the adverse conditions imposed by high-speed raindrops. Like flying insects, samaras descending from tall trees are likely to be struck by raindrops in an intense storm. In this study, we detail the collision dynamics for impact regions across the samara body and the drop-shedding mechanisms that samaras exhibit to return to autorotation. Impacts across the samara body can pitch the samara up to 60 degrees and, in some cases, induce spanwise roll. Raindrops may shatter or remain intact upon impact, pushing the undamaged samara downward before autorotation is recovered. Drops that strike near the wingtip elicit the greatest recovery distance, while impacts onto the nutlet mass are the least disruptive to the samara and most likely to cause the drop to induce fragmentation. Faster drops allow for quicker drop shedding and a subsequent rapid return to autorotation in less than 50 ms. Our results indicate that samaras are robust to raindrop impacts and consistently recover autorotation, resulting in a minor reduction in dispersal distance. To recover, the entire drop is shed from the spinning samara over a time closely tied to the shedding mode and ensuing drop rejection forces.We thank Colton Chandler, Andrew Fuson, and Colby Hale for their experimental contributions
Simulación numérica directa de samaras en autorrotación
No full textLas samaras son un tipo de fruto de árbol, con una semilla unida a una superficie sustentadora. Al caer del árbol, las samaras entran en autorrotación, generando una fuerza de sustentación que frena su caída y les permite recorrer grandes distancias arrastradas por el viento. El fenómeno es el mismo que premitió a Juan de la Cierva desarrollar su autogiro, y se produce por un balance entre las fuerzas aerodinámicas y las fuerzas de inercia para una actitud determinada de la samara. En esta charla, se presentarán resultados de simulaciones de samaras a bajo número de Reynolds, en las que las ecuaciones de Navier-Stokes se resuelven acopladas a las ecuaciones de Newton-Euler de conservación de momento lineal y angular del sólido. Los resultados se analizarán tanto desde el punto de vista cinemático, como desde el punto de vista de las estructuras que aparecen en el campo fluido. En concreto, se prestara especial atención al torbellino del borde de ataque (LEV, Leading Edge Vortex) que aparece en las samaras, muy parecido al que se observa sobre alas batientes y explica el aumento de sustentación de estas alas frente a alas fijas. El análisis de los distintos mecánismos que pueden explicar la estabilización del LEV muestra que, para los números de Reynolds considerados en este estudio, el efecto dominante parece estar relacionado con las fuerzas de inercia.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
Main interactions found for the proportion of seeds (full samaras) predated on the ground.
No full text<p>a) Relationship between microhabitat of samara deposition and guild of foragers; b) Relationship between natural samara availability and proportion of empty samaras. 0% empty samaras means that all samaras were full.</p
The physics of the spectacular flight of the Triplaris samaras
No full textSamaras are highly specialized forms of "flying" fruits that some species of trees produce for the dispersal of their
seeds in their environment. The flight of a samara is always a highly elaborated form of mechanical motion, and
an excellent opportunity for application of both Intermediate and Analytical Mechanics to a natural phenomenon.
One of the more interesting cases, the passive flight of Triplaris Caracasana, which is a combined motion of
vertical translation and simultaneous rotation, is presented here. A Newtonian Mechanics model is elaborated, and
successfully confirmed, using a variety of different and accurate laboratory measurement techniques including one
based on the chopping a laser beam. The motion of the flying samaras is indeed appealing and should be found of
great interest for Analytical Mechanics and Fluid Mechanics and as shown here for Intermediate Mechanics
courses.Las samaras son frutos �voladores�, altamente especializados, que algunas especies de árboles producen para
lograr dispersarse en su medio ambiente. El vuelo de una samara es siempre una forma muy elaborada de
movimiento mecánico, y una excelente oportunidad para la aplicación de la mecánica Analítica o de la Mecánica
Intermedia a un fenómeno natural. En este trabajo se presenta uno de los casos más interesantes, el vuelo
�pasivo� de la samara del árbol de nombre científico Triplaris caracasana, vuelo que es una combinación de
traslación vertical y rotación simultanea. Hemos elaborado un modelo basado en Mecánica Newtoniana de dicho
vuelo, el cual hemos además validado, y confirmado, mediante la aplicación de diferentes técnicas
experimentales, que incluyen una basada en la �interrupción periódica� (el llamado chopping en Inglés) del haz
de un laser. El movimiento de las samaras voladoras es sin duda atractivo y debe resultar de gran interés para la
Mecánica Analítica y la Mecánica de Fluidos y también, como lo demostramos aquí, para la Mecánica Intermedia
An evaluation of yellow-poplar samaras by radiography
No full textControl-pollinated samaras from 25 clones in a yellow-poplar breeding orchard at the University of Tennessee, Knoxville, were subjected to radiograph and germination analysis. A high correlation was found between filled samaras identified from radiographs and samaras that germinated. Significant differences were observed among clones used as females for percentage filled samaras; no such differences were present among pollen parents. Viability tended to be higher when clones were cross-pollinated than when the same clones were open-pollinated.
Analysis of 62 crosses and their reciprocals indicated significant difference between the two, thus, precluding a partial diallel analysis for viability and indicating a strong maternal effect.
An irradiation (gamma) study revealed that there is no significant effect with respect to germination and seedling dry weight from exposure to doses of radiation up to and including 2500R. Seedling length showed significant differences among treatments below 2500R with the two half-sib families used in the study reacting somewhat differently to the radiation treatment.
Statistical analysis of ten arbitrarily assigned zones of viability within several ripe gynoecia revealed that the topmost and lowermost (basal) samaras on the yellow-poplar cone are generally nonviable
The impact of watershed management on coastal morphology: A case study using an integrated approach and numerical modeling.
No full textCoastal morphology evolves as the combined result of both natural- and human- induced factors that cover a wide range of spatial and temporal scales of effect. Areas in the vicinity of natural stream mouths are of special interest, as the direct connection with the upstream watershed extends the search for drivers of morphological evolution from the coastal area to the inland as well. Although the impact of changes in watersheds on the coastal sediment budget is well established, references that study concurrently the two fields and the quantification of their connection are scarce. In the present work, the impact of land-use changes in a watershed on coastal erosion is studied for a selected site in North Greece. Applications are based on an integrated approach to quantify the impact of watershed management on coastal morphology through numerical modeling. The watershed model SWAT and a shoreline evolution model developed by the authors (PELNCON-M) are used, evaluating with the latter the performance of the three longshore sediment transport rate formulae included in the model formulation. Results document the impact of crop abandonment on coastal erosion (agricultural land decrease from 23.3% to 5.1% is accompanied by the retreat of ~ 35 m in the vicinity of the stream mouth) and show the effect of sediment transport formula selection on the evolution of coastal morphology. Analysis denotes the relative importance of the parameters involved in the dynamics of watershed–coast systems, and – through the detailed description of a case study – is deemed to provide useful insights for researchers and policy-makers involved in their study
Meteorological observations during DORTENAAR cruise from Samaras to Batavia started at 1835-04-05
No full textMeteorological observations during DORTENAAR cruise from Samaras to Batavia started at 1835-04-0
Meteorological observations during DORTENAAR cruise from Oudjong Pancer to Samaras started at 1835-03-17
No full textMeteorological observations during DORTENAAR cruise from Oudjong Pancer to Samaras started at 1835-03-1
- …
