Microgravity Science and Technology最新文献

{"title":"Numerical Study on Bubble Generation and Departure Characteristics from Submerged Orifices in Viscoelastic Fluids","authors":"Ziyi Yang,&nbsp;Mingjun Pang","doi":"10.1007/s12217-026-10264-1","DOIUrl":"10.1007/s12217-026-10264-1","url":null,"abstract":"<div><p>In this study, a two-dimensional axisymmetric model is established using OpenFOAM. The bubble interface is captured using the volume of fluid method, where the liquid’s viscoelastic behavior is characterized by the Giesekus model. The authors systematically investigated bubble formation in viscoelastic liquids, focusing on the effects of rheological parameters (such as zero-shear viscosity, relaxation time, and mobility factor) and operating conditions (gas injection velocity and orifice radius) on bubble evolution (such as aspect ratio, contact line diameter, and duration of each stage) and departure behaviors (including departure time and volume). By analyzing the evolution of bubble contact line diameter and bubble height, bubble formation process can be divided into five stages: (1) nucleation, (2) expansion, (3) elongation, (4) retraction, and (5) departure. The present results indicate that mobility factor exerts a comparatively minor impact on bubble evolution and departure. In contrast, with increasing relaxation time, the apparent viscosity and the elastic stress of liquid decrease significantly, leading to a marked change in bubble morphology. Specifically, the bubble tail gradually changes from a pointed shape to a concave shape, and the gas line also presents at the bubble tail. Both the contact line diameter and the maximum pre-departure bubble height decrease with increasing relaxation time, but they increase with increasing zero-shear viscosity, injection velocity, and orifice radius. Departure time increases only with zero-shear viscosity and decreases with all other parameters studied. Bubble departure volume decreases solely with increasing relaxation time but it grows with an increase in the other parameters.</p></div>","PeriodicalId":707,"journal":{"name":"Microgravity Science and Technology","volume":"38 4","pages":""},"PeriodicalIF":1.5,"publicationDate":"2026-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s12217-026-10264-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148380374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An Experimental Study on Piloted Ignition of Solid Materials Under Low-Velocity Flow Environment","authors":"Kai Zhang,&nbsp;Feng Zhu,&nbsp;Zhanbin Lu,&nbsp;Shuangfeng Wang","doi":"10.1007/s12217-026-10265-0","DOIUrl":"10.1007/s12217-026-10265-0","url":null,"abstract":"<div><p>The ignition of solid materials is strongly influenced by environmental conditions, including flow velocity, oxygen concentration, and ambient pressure. Understanding ignition behaviors at low flow velocities is of paramount importance for spacecraft fire safety. In this study, the ignition process of thermally thick solid fuels is systematically investigated using a narrow-channel apparatus, with a specific focus on low-flow-velocity regimes. Within the tested parametric range, transient flame flashes are observed, the duration of which depends on the flow velocity, indicating a complex transport phenomenon driven by limited oxygen supply. Both the ignition delay time and the corresponding critical mass flux exhibit a non-monotonic dependence on flow velocity; that is, they decrease, reach minimum values at approximately 5 cm/s, and subsequently increase until ignition fails. This paper proposes an improved model for predicting the critical mass flux for ignition by explicitly accounting for the unique mass transport characteristics in low-flow-velocity environments. The model predictions demonstrate good agreement with both the present experimental results and existing literature data. Furthermore, by integrating this critical mass flux criterion with a comprehensive solid-phase degradation model, a one-dimensional transient ignition model is developed. By incorporating the additional heat feedback from the transient flashing flame at low velocities, this comprehensive model successfully reproduces the observed non-monotonic trend of the ignition delay time. The proposed modeling framework can also be extended to predict flame spread rates, thereby establishing a quantitative link between ignition and flame spread process.</p></div>","PeriodicalId":707,"journal":{"name":"Microgravity Science and Technology","volume":"38 4","pages":""},"PeriodicalIF":1.5,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148380465","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of Gravity on Hydrogen/Air Flame Propagation in Straight and Curved Tubes with Different Placement Angles","authors":"Haoyang Fan,&nbsp;Jinbo Cheng,&nbsp;Wang Han,&nbsp;Yihao Tang,&nbsp;Wenjun Kong,&nbsp;Lijun Yang","doi":"10.1007/s12217-026-10266-z","DOIUrl":"10.1007/s12217-026-10266-z","url":null,"abstract":"<div><p>Understanding the effects of gravity on hydrogen-air flame propagation dynamics in straight and curved tubes is crucial for mitigating the fire and explosion risks associated with hydrogen. The impact of gravity on flame propagation is expected to depend on the angle between the gravity and flame-propagation directions, but this relationship remains poorly understood. In this study, we numerically investigated the propagation characteristics of hydrogen/air flames in straight and curved open-ended tubes, focusing on how tube placement angle affects flame propagation. The results reveal that variations in tube placement angle, together with the effects of gravity and curvature on pressure gradients, can significantly influence unburned-gas flow and thereby alter flame propagation, particularly in curved tubes. Flame propagation could be substantially influenced by gravity. The evolution of the flame front is analyzed using the vorticity equation and baroclinic torque, showing that in straight tubes, the flame tilt direction changes with tube placement angle. In contrast, the bend of curved tubes consistently directs the flame front toward the inner wall. Gravity induces two distinct flame structures in the transitional regime of curved tubes, thereby affecting flame-front evolution and propagation through the stretch rate and displacement velocity. These findings highlight the crucial role of tube orientation in flame propagation, underscoring the potential fire hazards associated with hydrogen utilization.</p></div>","PeriodicalId":707,"journal":{"name":"Microgravity Science and Technology","volume":"38 4","pages":""},"PeriodicalIF":1.5,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148380425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Differential Effects of Vibration on Bone Tissue in Zebrafish","authors":"Juan D. Carvajal-Agudelo,&nbsp;Tamara A. Franz-Odendaal","doi":"10.1007/s12217-026-10263-2","DOIUrl":"10.1007/s12217-026-10263-2","url":null,"abstract":"<div><p>Low-level vibration exposures are known to affect multiple tissues in living organisms. This study investigates the effects of vibration exposure on bone tissue in larval zebrafish (<i>Danio rerio</i>). Larvae were exposed to vibrations (44–50 Hz) for 24 h, with or without anaesthesia, and were compared to controls. Ossification levels of the larval skeleton together with the expression of <i>colX</i> (a marker of bone development) in the operculum bone was used to determine the morphological response to vibrations. Gene expression of bone-related (<i>acp5a</i>,<i> bglap</i>,<i> rankl</i>) and apoptosis-related markers (<i>bax</i>) was then evaluated via RT-qPCR after the 24-hour exposure as well as one week after treatment. Results showed no significant differences in overall ossification or <i>colX</i> expression due to vibration. However, gene expression analyses revealed transient changes: all genes were affected immediately after vibration in contrast to one week later, when only <i>acp5a</i> and <i>bglap</i> were affected. These findings suggest that while short-term low-frequency vibration does not visibly affect bone morphology, it can influence bone homeostasis at the molecular level. Our study also underscores the need for appropriate vibration controls in ground-based simulated microgravity studies in order to assess the impact of vibrations from equipment used (e.g. incubators, or other platforms), particularly in gene expression experiments.</p></div>","PeriodicalId":707,"journal":{"name":"Microgravity Science and Technology","volume":"38 4","pages":""},"PeriodicalIF":1.5,"publicationDate":"2026-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148285416","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermocapillary Droplet Flow in Small-scale Containers: the Effect of Gravity","authors":"Mohammad K. Alhamli,&nbsp;Yousuf Alhendal,&nbsp;Hussain Al-Sairfi","doi":"10.1007/s12217-026-10253-4","DOIUrl":"10.1007/s12217-026-10253-4","url":null,"abstract":"<div><p>We numerically investigate the motion of a Fluorinert FC-75 droplet suspended in silicone oil in a cylindrical container under a vertical temperature difference. The top and bottom walls are maintained at 343 and 283 K, the sidewall is adiabatic, and the droplet is initially placed at mid-height. Ansys Fluent with the Volume of Fluid method is used to solve the coupled momentum and energy equations. Container heights from 2.5 to 60 mm are examined, with droplet diameter scaled with container size, under zero gravity, normal gravity, and combined thermocapillary-buoyancy forcing. In zero gravity, the droplet migrates toward the hot upper wall, but its mean migration speed decreases as container height increases because the axial temperature gradient weakens and confinement distorts the isotherms. Under normal gravity, the denser FC-75 droplet settles toward the cold wall. Under combined forcing, containers with heights of 3 mm or less exhibit near cancellation between buoyancy and thermocapillary, whereas for heights of 15 mm or more the motion approaches the gravity dominated limit. At a fixed height of 2.75 mm, varying droplet diameter reverses the net drift. This transition is captured by a Marangoni-buoyancy balance criterion, which predicts a critical diameter of about 0.203 mm for quasi-equilibrium. Three-dimensional simulations show deformation only in the buoyancy dominated regime. These results identify confined configurations that approximate microgravity behavior and provide a practical criterion for droplet positioning and transport.</p></div>","PeriodicalId":707,"journal":{"name":"Microgravity Science and Technology","volume":"38 3","pages":""},"PeriodicalIF":1.3,"publicationDate":"2026-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148237371","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"In Situ Observation of Shrimp Feeding Process Under Microgravity Environment","authors":"Chihiro Yokota,&nbsp;Souta Kumano,&nbsp;Seiichi Tsumura,&nbsp;Kanji Kameyama,&nbsp;Syou Maki,&nbsp;Ryosuke Tadokoro,&nbsp;Toshimasa Yamamoto","doi":"10.1007/s12217-026-10262-3","DOIUrl":"10.1007/s12217-026-10262-3","url":null,"abstract":"<div><p>We carried out an in situ observation of the feeding process of edible shrimp in a microgravity environment. To realize that condition, we developed a new type of clinostat with high-speed rotation, with a maximum rotation of 130 rpm. Under that rotation speed, aquatic organisms such as fish and crustaceans have a suppressed capability of recovering their proper swimming form, making it possible for them to be exposed to a pseudo-weightless condition. This method allowed us to successfully observe the feeding process of shrimp in that condition. As a supporting experiment, we conducted similar experiments using larval <i>Artemia crustaceans</i>, i.e. brine shrimp, and we confirmed that they, too, can exhibit feeding behavior under a weightless environment, even when exposed for the long period of four days. According to a gene ontology analysis of shrimp exposed to microgravity for 24 h, a significant difference was detected in the exposed shrimp as compared with control shrimp at 1 G. Those results suggested that exposure to weightlessness may have a biological impact on the shrimp, although the details are unknown yet. We believe that the high-speed clinostat will contribute greatly to the future progress of engineering applications in microgravity research.</p></div>","PeriodicalId":707,"journal":{"name":"Microgravity Science and Technology","volume":"38 3","pages":""},"PeriodicalIF":1.3,"publicationDate":"2026-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148236570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Clinorotation Compensates for the Curvature of Spinach Roots Under Normal Gravity","authors":"Shusaku Nakajima,&nbsp;Takuma Genkawa","doi":"10.1007/s12217-026-10259-y","DOIUrl":"10.1007/s12217-026-10259-y","url":null,"abstract":"<div><p>To examine growth patterns of a leafy vegetable under simulated microgravity, spinach seedlings were cultivated under clinorotation at 2 rpm in darkness for 5 d and compared with control seedlings grown under normal gravity. No significant differences were detected in root length and water content between the two growth conditions. However, interestingly, seedlings under clinorotation showed straight elongation, whereas curvature and waving appeared in control roots. Consequently, roots under clinorotation had significantly higher straightness, calculated as the straight line between the root base and tip divided by the actual root length. As the phytohormone auxin is involved in root bending, spinach seedlings were further cultivated in the presence of auxin inhibitors. Under inhibitor treatment, no significant difference in root straightness was observed between clinorotation and control, and the values were comparable to those of seedlings under clinorotation without an auxin inhibitor. These findings suggest that auxin contributes to the curvature of the control seedlings and clinorotation compensates for this. Therefore, spinach seedlings at the early developmental stage exhibited a unique growth pattern under clinorotation, unlike most other plant species.</p></div>","PeriodicalId":707,"journal":{"name":"Microgravity Science and Technology","volume":"38 3","pages":""},"PeriodicalIF":1.3,"publicationDate":"2026-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s12217-026-10259-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148173136","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermocapillary Interaction of Two Aligned Compound Droplets in a Constricted Microchannel","authors":"Vinh T. Nguyen,&nbsp;Nang X. Ho,&nbsp;Vinh D. Nguyen,&nbsp;Kien T. Nguyen,&nbsp;Truong V. Vu","doi":"10.1007/s12217-026-10260-5","DOIUrl":"10.1007/s12217-026-10260-5","url":null,"abstract":"<div><p>While the thermocapillary migration of single and compound droplets has been extensively studied in unbounded media, the synchronized transport and interaction dynamics of multiple compound droplets within confined geometries remain poorly understood. This study addresses this gap by numerically investigating the thermocapillary migration of two axially aligned compound droplets inside a microchannel featuring a localized geometric constriction. Using the front-tracking method, we aim to delineate the transition between interacting and non-interacting regimes, a distinction critical for the precise control of multi-phase flows in microfluidic systems. The coupled thermal and hydrodynamic behaviors are systematically analyzed as a function of the Marangoni number (<i>Ma</i>), the axial positioning of the leading droplet, the inner-to-outer droplet size ratio (<i>R</i>_<i>io</i>), and the relative constriction depth (<i>d/R</i>_<i>c</i>). Our results reveal that inter-droplet interaction is primarily triggered when the trailing droplet catches up to the leading one near the constriction, where local velocity reaches its minimum. We identify <i>Ma</i> as a dominant control parameter; higher <i>Ma</i> values intensify thermal convection, which disrupts the local temperature field and delays the onset of interaction by reducing the trailing droplet’s velocity. Crucially, we find that geometric and internal configurations dictate the interaction mode: shallow constrictions (<i>d/R</i>_<i>c</i> &lt; 0.58) or larger inner cores (<i>R</i>_<i>io</i> ≥ 0.7) promote independent passage by enabling droplet elongation or rapid escape. In contrast, deeper constrictions and smaller inner cores reduce interfacial deformation, thereby facilitating closer proximity and significant multi-body interaction. The study culminates in the establishment of a comprehensive phase diagram based on <i>H</i>_0<i>L</i><i>/R</i>_<i>o</i>, <i>R</i>_<i>io</i>, and <i>Ma</i>. This diagram serves as a predictive tool to define the boundaries between interacting (<i>ID</i>* = 0) and non-interacting (<i>ID</i>* &gt; 0) regimes. By providing a mechanistic understanding of how geometry and thermal forces can be leveraged to synchronize or separate double emulsions, this work offers a framework for the optimized design of microfluidic devices for targeted drug delivery and advanced material synthesis.</p></div>","PeriodicalId":707,"journal":{"name":"Microgravity Science and Technology","volume":"38 3","pages":""},"PeriodicalIF":1.3,"publicationDate":"2026-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148172570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical Study of Crucial Effect of Forced Convection on the Structure of PMMA Flame Under Microgravity Conditions","authors":"Tatyana Bolshova,&nbsp;Vladimir Shvartsberg","doi":"10.1007/s12217-026-10258-z","DOIUrl":"10.1007/s12217-026-10258-z","url":null,"abstract":"<div><p>Present work involves numerical CFD study of the flame structure of PMMA sphere at different velocities of the incident oxidizer flow under zero-gravity conditions. The performed modeling allowed us to establish the chemical processes to change significantly with a variation of velocity of the oxidizer flow. It was shown that both the thermal and chemical structure of the flame change, as well as the temperature gradient and the mechanism of heat release in the gas phase. It has been established that with an increase in the flow velocity, the combustion completeness decreases that is explained by an increase in the flame strain rate and, consequently, a decrease in the residence time in the chemical reaction zone. Calculation of the heat release rates in individual reactions at various oxidizer flow velocities allowed us to identify four key reactions determining the overall heat release rate. At average flow velocity values, the main contribution to the heat release is made by the HO₂ + OH = H₂O +O₂ step, which is explained by a high concentration of HO₂ in the flame. The remaining key steps in decreasing order of their contribution to the heat release are T-C₃H₅ + O₂ = CH₃ + CO + CH₂O, HCO + O₂ = CO + HO₂ and CH₃ + O = H + H₂ + CO.</p></div>","PeriodicalId":707,"journal":{"name":"Microgravity Science and Technology","volume":"38 3","pages":""},"PeriodicalIF":1.3,"publicationDate":"2026-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148009229","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sounding Rockets for Gravitational Research on Plants: A Systematic Review","authors":"Fateme Mousavi","doi":"10.1007/s12217-026-10242-7","DOIUrl":"10.1007/s12217-026-10242-7","url":null,"abstract":"<div><p>The ability of plants to adapt and grow in extraterrestrial environments is a crucial prerequisite for human spatial colonization of extraterrestrial environments. Sounding rockets allow biological payloads to experience real microgravity conditions for several minutes before returning to Earth. The present systematic review sought to gain new insights to guide the design of plant experiments for sounding rocket platforms. Most of the plant studies using sounding rocket technology have been conducted by Germany (Ten out of twelve launches). In the launches conducted, the minimum apogee was 86 km, and the maximum was 800 km for the Virgin Galactic Unity 22 and MAXUS, respectively. The microgravity quality was in the range of 10^− 4 g to 10^− 6 g. The plant payloads selected for the launches ranged from plant cells to young seedlings. Four (4) out of 10 studies deploy hardware capable of automatically fixing the plant material in different gravitational phases. All ten studies included 1 g ground controls in parallel with the flown samples. Two of the ten studies utilized another real microgravity platform in addition to 1 g ground controls, conducted in parallel with the sounding rocket flight. The biological responses to sounding rocket flight have been investigated at cellular, molecular, histological, and physiological levels. Sounding rockets and suborbital spacecraft, even though they have some limitations, can still be good options for plant biology researchers. They offer a way to do repeated observations and experiments in real microgravity conditions.</p></div>","PeriodicalId":707,"journal":{"name":"Microgravity Science and Technology","volume":"38 3","pages":""},"PeriodicalIF":1.3,"publicationDate":"2026-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148008914","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}