Warm Fluid Research Articles

Thermohydraulic performance and effectiveness of a mini shell and tube heat exchanger working with a nanofluid regarding effects of fins and nanoparticle shape

The influence of varied nanoparticle shapes on thermal–hydraulic efficacy of a boehmite nanofluid (BNF) in a mini shell and tube heat exchanger (MSTHX) in the cases of with and without fin is investigated. The five nanoparticle shapes with 90 °C inlet temperature at Reynolds number of 500 for the warm fluid side, and four Reynolds numbers of 500, 1000, 1500, and 2000 with 20 °C inlet temperature for the cold fluid side are considered. The warm fluid is the nanofluid that moves in the tube side, whilst the cool fluid is common water inside the shell side. With elevating Reynolds number, the heat transfer rate (q), overall heat transfer coefficient (U), pressure drop, effectiveness, and number of transfer unit (NTU) increase, while the performance index reduces. By increasing the Reynolds number from 500 to 2000 in the nanofluid having the oblate spheroid nanoparticles, the effectiveness rises 20%, and the performance index reduces 21.7%. The BNF with the platelet additives results in the largest q, whilst the smallest pressure loss is achieved for the Os-shaped additives. Also, the heat transfer rate, U, effectiveness, NTU, performance index, and pressure loss for the MSTHX with fin are larger than those for the MSTHX without fin.

Caveat Emptor: The Heat Is "ON"-An In Vivo Evaluation of the Thulium Fiber Laser and Temperature Changes in the Porcine Kidney During Dusting and Fragmentation Modes.

Introduction: We sought to examine the intrarenal fluid and tissue temperature alterations during dusting and fragmentation with the thulium fiber laser (TFL) in an in vivo porcine kidney. Materials and Methods: In two female Yorkshire pigs, temperature was continuously measured within the upper, interpolar, and lower calices along with the renal pelvis using multipoint thermal sensor probes; another temperature probe was situated at the tip of the ureteroscope. Four experimental protocols were performed for each animal: dual lumen ureteroscope with both warmed (37°C) irrigation and room temperature (20°C-22°C) irrigation and single lumen ureteroscope with warmed and room temperature irrigation. Of note, in each pig, one kidney underwent ureteroscopy (URS) with a 14F ureteral access sheath (UAS) in place, whereas the other kidney had no UAS placed. A 200-μm TFL fiber was fired at three laser settings: (1) dusting at 0.5 J, 80 Hz (40 W) with continuous activation until 5 minutes expired or a temperature of 44°C was reached, (2) low-power fragmentation 1 J, 10 Hz, (10 W), and (3) high-power fragmentation at 1.5 J, 20 Hz (30 W). In all cases, the pulse width was 1 ms. For fragmentation, the laser was activated for 10 seconds with a 2-second intermission for a 1-minute period (five cycles). Results: In the absence of a UAS, in all but one circumstance, temperatures reached or exceeded 44°C at all laser settings with the use of either warm or room temperature irrigation fluid, regardless of the type of ureteroscope used. Of concern, temperatures recorded at the tip of the URS were 4°C to 22°C less than the temperatures recorded in the renal calices. In contrast, with a 14F UAS in place, six distinct groups had temperatures that did not exceed 44°C, specifically at low- and high-power fragmentation settings with room temperature irrigation for both sets of ureteroscopes and at dusting and low-power fragmentation settings with warm temperature irrigation solely for the single lumen ureteroscope. Temperatures recorded at the tip of the ureteroscope with the deployment of a UAS yielded temperature differences ranging from 17°C less to 19°C more than the renal calices. Conclusions: TFL is a novel laser technology for lithotripsy. In the absence of a UAS, high-power TFL fragmentation settings in particular may create temperatures within the collecting system that could result in urothelial tissue injury. Of note, peak temperatures recorded at the tip of the ureteroscope may misrepresent the actual intrarenal temperature during TFL laser lithotripsy.

Fluid Histories of Middle Ordovician fault–fracture hydrothermal dolomite oil fields in the southern Michigan Basin, U.S.A.

ABSTRACTDolomitized fault–fracture structures in the Trenton and Black River formations (TBR) are the type example for “hydrothermal” petroleum reservoirs world-wide. However, fluid histories of these structures are only partially understood. Trenton and Black River reservoirs in the southern Michigan Basin are composed of fault-associated, vertical dolomite bodies that are highly fractured and brecciated. Open spaces are partially to completely filled by saddle dolomite and less frequently by calcite cement. Cathodoluminescence microstratigraphies of void-filling carbonate cements are not correlatable between oil fields. Fluid inclusion homogenization temperatures (Th) measured in carbonate cements indicate two fluid endmembers: a warm fluid (∼ 80° to 180° C) and a hot fluid (180° to ∼ 260° C). Increasing Th proximal to the underlying Proterozoic Mid-Michigan Rift (MMR) suggest that the hot fluids emanated from the rift area. Included fluids are saline (16.1–49.4 wt. % NaCl equivalent), and salinity likely is sourced from overlying Silurian Salina Group evaporites. First melting temperatures (Tfm), interpreted as eutectic temperatures (Te), of fluids range from –112° C to –50° C, indicating a complex Na–Ca–KCl brine; the expected composition of dissolved Salina salts. Lower Te proximal to the MMR suggest the rift as a source of additional complexing ions. C and O isotope values for carbonate cements are depleted with respect to δ18O (–6.59 to –12.46‰ VPDB) relative to Ordovician seawaters, and somewhat depleted with respect to δ13C (–1.22 to +1.18‰ VPDB). Equilibrium calculations from δ18O and Th values indicate that cement precipitating waters were highly evolved (+1.3 to +14.4‰ δ18O‰ VSMOW) compared to Ordovician and Silurian seawaters (–5.5‰ δ18O‰ VSMOW). Strontium isotope values indicate two fluid sources: Proterozoic basement and Late Silurian evaporites. Values of 87Sr/86Sr for cements in the Freedom, Napoleon, Reading, and Scipio fields (0.7086–0.7088) are influenced by warm water sourced from Silurian strata, and values for cements in the Albion, Branch County, and Northville fields (0.7091–0.7110) record continental basement signatures. Cement precipitating fluids in TBR oil fields likely have similar sources and timing. However, water–rock interactions along fault pathways modified source waters, giving each oil field a unique petrographic and geochemical signature. Fluid movement in TBR oil fields likely were initiated by reactivation of basement faulting during Silurian–Devonian tectonism.

A simple improvised prehospital method to warm intravenous fluid.

Study ObjectiveUse of warmed intravenous fluid by emergency medical services (EMS) for prehospital injured patients is recommended to avoid iatrogenic hypothermia. We hypothesized that an improvised heating method would significantly increase the temperature of an intravenous fluid bag in a simulated prehospital environment.MethodsThe change from baseline in the temperature of a 1‐L intravenous fluid bag positioned above the vehicle windshield defroster vent was measured for 30 minutes using a thermocouple probe. Temperature changes were compared with a control fluid bag positioned on the vehicle console armrest. A total of 10 independent experiments were performed.ResultsThe defroster vent method increased intravenous fluid bag temperature from a mean starting temperature of 19.4°C (95% confidence interval [CI], 17.4°C–21.4°C) to a mean end temperature of 32.6°C (95% CI, 30.6°C–34.6°C) after 30 minutes. The temperature of a control intravenous fluid bag (mean starting temperature of 20.1°C; 95% CI, 19.0°C–21.2°C) exposed to a warmed (mean 33.2°C) passenger compartment changed little during the same time period (mean end temperature of 22.3°C; 95% CI, 19.4°C–25.2°C).ConclusionsConvective warming of an intravenous fluid bag using the dashboard defroster vent significantly raised the fluid temperature. Such a method should be readily available to EMS or first responders.

Wave-driven torques to drive current and rotation

In the classic Landau damping initial value problem, where a planar electrostatic wave transfers energy and momentum to resonant electrons, a recoil reaction occurs in the nonresonant particles to ensure momentum conservation. To explain how net current can be driven in spite of this conservation, the literature often appeals to mechanisms that transfer this nonresonant recoil momentum to ions, which carry negligible current. However, this explanation does not allow the transport of net charge across magnetic field lines, precluding E × B rotation drive. Here, we show that in steady state, this picture of current drive is incomplete. Using a simple Fresnel model of the plasma, we show that for lower hybrid waves, the electromagnetic energy flux (Poynting vector) and momentum flux (Maxwell stress tensor) associated with the evanescent vacuum wave become the Minkowski energy flux and momentum flux in the plasma and are ultimately transferred to resonant particles. Thus, the torque delivered to the resonant particles is ultimately supplied by the electromagnetic torque from the antenna, allowing the nonresonant recoil response to vanish and rotation to be driven. We present a warm fluid model that explains how this momentum conservation works out locally, via a Reynolds stress that does not appear in the one-dimensional initial value problem. This model is the simplest that can capture both the nonresonant recoil reaction in the initial-value problem, and the absence of a nonresonant recoil in the steady-state boundary value problem, thus forbidding rotation drive in the former while allowing it in the latter.

Pyritic mineralization halo above the Tara Deep Zn-Pb deposit, Navan, Ireland: Evidence for sub-seafloor exhalative hydrothermal processes?

The Tara Deep Zn-Pb deposit, at Navan, Ireland, includes sub-economic pyrite-rich mineralization extending laterally for about 2 × 2 km within the overlying Lower Viséan calc-turbidites, known as the ‘New-Thin Bedded Unit’. Here, we investigate the genesis of this pyritic mineralization and its links to the limestone-hosted Zn-Pb deposit lying 100 m below it.Four mineral assemblages have been identified: 1) in black shales, laminated pyrite comprises thin framboid-rich layers with minor interstitial sphalerite, both showing variable but low δ34S values ranging from −37.4 to 3.3‰; 2) in calcarenite and calcsiltite layers, pyritized fossils are widely distributed and occur chiefly as biodebris replaced by low δ34S pyrite (mean values of −13.2‰); 3) a replacive assemblage occurs as late remobilizations exhibiting both crosscutting and bedding-parallel styles, overprinting the early laminated pyrite. It comprises mostly of marcasite, with minor pyrite, sphalerite, chalcopyrite, galena, stibnite and Co-pentlandite, with high δ34S values up to 24.5‰; and 4) in black shales, bedded sulfide-rich cherts comprising microcrystalline quartz lenses exhibit δ18O mean values of 25.3‰. Cherts are rimmed by dolomite, associated with marcasite, pyrite, sphalerite, chalcopyrite, galena, siegenite and stibnite also with high δ34S values up to 44.2‰. In general terms, pyrite shows a relatively high Co/Ni ratio > 1 and sphalerite Zn/Cd ratios vary from 268 to 364.Textural analysis indicates overlapping of early-diagenetic and multi-phase hydrothermal sulfide mineralization. Development of laminated pyrite and pyritized calcarenites suggests that this mineralization was generated during early diagenesis, close to the seawater-sediment interface in oxygen-poor conditions under the influence of low-temperature hydrothermal fluid circulation. Later hydrothermal cherts and replacive sulfides suggest discharge of relatively warm hydrothermal fluids during early to mid-diagenesis, presumed to be linked to movements of nearby normal faults. Similarities in mineralogy and S isotope compositions suggest genetic links between the sub-economic pyritic mineralization and the underlying Tara Deep deposit, and consequently, that the former represents a geochemical halo with direct applicability in exploration for Zn-Pb deposits.

Warming of blood and intravenous fluids using low-power infra-red light-emitting diodes

Non-contact warming of blood and intravenous (IV) fluids with temperature drop compensation is an unmet clinical need till now, for management of hypothermia in patients with urgent requirement of blood. Currently available technologies provide wet warming or dry warming with direct contact using hot water or with a hot plate, respectively. These conventional technologies need disposable cartridges to be used in conjunction with the warmer. The warmed fluids lose their temperature when passing through long IV lines and fails in its purpose at low flow rates. In this paper, a distributed non-contact warming method is introduced using infra-red radiations. The method incorporates a bag warming unit and an inline cartridge unit. Bag warming unit provides uniform distribution of infra-red thermal energy liberated from low cost infra-red light emitting diodes (IR LEDs) in horizontal and vertical planes of the fluid carrying bag. An inline cartridge, through which the IV line passes, reduces the drop in temperature just before the transfusion site using a cluster of IR LEDs. As per the In Vitro tests are carried out in to establish the safety and efficacy, the bag warming unit steadily rises the temperature to attain the cut off value with a temperature rise coefficient of 0.7 °C/min and the inline cartridge warms the fluid within 10 min at a thermal transfer rate of more than 1.5 °C/min. The fluid temperature is uniformly distributed within a narrow range of 36–38 °C. When the inline warmer is powered on, the drop-in temperature is reduced to zero for flow up to 5 ml/min. For flow rates more than 8 ml/min, the temperature drop is reduced more than half. For massive transfusion range, the temperature of the fluid remains within 38.5 ± 1.2 °C for flow rates in the range of 100–1500 ml/min.

Parametric evaluation of the combined solar driven precompression supercritical CO2 cycle and organic Rankine cycle using ultra low global warming potential fluids

In this paper, thermodynamic parametric analysis of solar driven pre-compression cycle combined with super critical CO2 and organic Rankine cycle using zero ozone depletion (ODP) and ultra low global warming potential (GWP) fluids have been carried out. The thermal model for the above system was developed using low global warming potential fluids and it was found that the thermal performance of the system is increased with the concentration ratio, fluid velocity, and with solar irradiation while decreased with receiver emittance. In terms of thermal performance parameters the R1224yd(E) gives highest performance Maximum exergy efficiency, thermal efficiency and output power were increased from 36.73% to 58.52%, 34.16% to 54.42% and 183kW to 293.5kW respectively when DNI (direct normal irradiation) increased from 0.4 kW/m2 to 0.95 kW/m2 based on R1224yd(E) fluid. R1224yd(E) recommended for the better performance.

A Rapid Numerical Method to Constrain 2D Focused Fluid Flow Rates Along Convergent Margins Using Dense BSR‐Based Temperature Field Data

AbstractEstimates of the sub‐seabed fluid flow rates are important for understanding hydrological budgets, biogeochemical cycles, and physical properties of the sediments. Fluid flow rates and directions, however, are difficult to measure, particularly beneath the seafloor. We developed a rapid method to estimate regional fluid migration rates using an extensive database of seismic reflection profiles taken offshore SW Taiwan. We observe bottom‐simulating reflector (BSR) that deflects toward the seafloor near thrust faults that indicate localized heat flow variations. At these sites, advecting warm pore fluids transport heat to shallower depths and force the BSR shallower. Our 2D steady‐state numerical method quantifies the fluid flow rates required to cause such thermal anomalies. We found that fluid flow rates near the trench of the accretionary wedge range between 0.1 and 16 m3 yr−1 m−1, with slower and faster rates generally associated with slope basin discontinuities and faults, respectively. To evaluate the fluid pattern evolution from subduction to collision, we studied three transects: one along the Manila subduction zone in the south and two in Taiwan's initial collision zone in the north. We quantified the fluid budget and partitioning of fluid flow between focused discharge through faults and diffusive flow through the wedge. Faults in Taiwan's accretionary wedge capture on average 25% of the total dewatering flux in the younger subduction zone and 38.5% in the tectonically mature collision zone. Our method provides estimates of fluid migration rates along convergent plate boundaries, and contributes to our understanding of focused fluid flow processes in many other regions.

Warm distension fluid reduces pain severity in office hysteroscopy: a randomized controlled trial.

BACKGROUND: Abnormal uterine bleeding (AUB) affects approximately 14% to 25% of women of reproductive age. The most common use of office hysteroscopy is to evaluate pathologies related to AUB and reproductive health, but office hysteroscopy can also be used for the diagnosis and treatment of other intrauterine pathologies.OBJECTIVE: Investigate the effects of the temperature of the distension fluid on pain severity in patients undergoing diagnostic office hysteroscopy due to AUB.DESIGN: Randomized controlled clinical trial.SETTING: Tertiary care center in Turkey.PATIENTS AND METHODS: One hundred perimenopausal patients with AUB were randomly allocated according to the temperature of the distension fluid used in office hysteroscopy (37°C or 25°C). Pain intensity was assessed using a visual analog scale (VAS). Six VAS measurements were compared over the course of the hysteroscopy: pre-treatment (VAS-1), at vaginal entry (VAS-2), at the cervical ostium transition (VAS-3), while in the cavity (VAS-4), at the end of the procedure (VAS-5), and 30 minutes after the end of the procedure (VAS-6).MAIN OUTCOME MEASURE: VASSAMPLE SIZE: Fifty in each group enrolled, one drop out.RESULTS: The VAS-3, VAS-4, and VAS-5 scores were significantly lower for patients in the warm fluid group than in the room temperature group (P<.05), whereas the VAS-1, VAS-2, and VAS-6 scores were similar in both groups.CONCLUSION: The application of warm distension fluid in office hysteroscopy reduces pain severity compared with the application of an unheated fluid.LIMITATIONS: The main limitations of the study were that a subgroup analysis could not be performed due to an insufficient number of cases, and we were unable to evaluate vasovagal symptoms.CONFLICT OF INTEREST: None.

Irreversibility features of a shell-and-tube heat exchanger fitted with novel trapezoidal oblique baffles: Application of a nanofluid with different particle shapes

The influences of nanoparticle shape on the Entropy Generation Rate (EGR) of a boehmite nanofluid in a shell and tube heat exchanger fitted with trapezoidal oblique baffles are investigated. The hot fluid is the nanofluid with five particle shapes (i.e., platelet, cylinder, blade, brick, and oblate spheroid), whereas the cold fluid is selected to be water. The hot fluid streams at the tube-side, while the cold fluid streams at the shell-side. By the elevation of the Reynolds number (Re), in the warm fluid, the thermal and frictional entropy productions increase, while the Bejan number reduces. The nanofluid with platelet-shaped nanoparticles results in the greatest frictional EGR and thermal EGR in the hot fluid, pursued by the suspensions with the cylinder-, blade-, brick-, and Os-shaped nanoparticles, respectively. By rising the Reynolds number, in the cold fluid, the thermal EGR reduces, and the frictional EGR increases. The nanofluid with Os-shaped particles shows the highest thermal and frictional entropy productions in the cold fluid. All in all, with considering the whole heat exchanger regarding the second law of thermodynamics, the platelet-shaped particles are the best ones to be utilized in the heat exchanger, resulting in the lowest irreversibility.

Simultaneous tomographic particle image velocimetry and thermometry of turbulent Rayleigh–Bénard convection

This paper presents a non-intrusive measurement technique for the simultaneous assessment of the three-dimensional (3D) velocity and temperature fields in thermal convection. The technique is based on the combination of tomographic particle image velocimetry and particle image thermometry. Thermochromic liquid crystal particles serve simultaneously as both flow tracers and thermometers. The velocity fields were measured in a volume of 62 500 cm3 and the temperature fields in a subvolume of 20 000 cm3. Turbulent Rayleigh–Bénard convection in a water-glycol mixture at and was used as a model system to measure the instantaneous 3D velocity and temperature fields at the same time. Uncertainties of mm s−1 for the velocity and K for the temperature measurement were estimated corresponding to dynamic ranges of 24 and 21 levels, respectively. Correlating the measured temperature and velocity fields, it is shown that the obtained large-scale structure reflects a region of warm rising fluid which is well-known from the literature.

Aluminium release and fluid warming: provocational setting and devices at risk

BackgroundFluid warming, recommended for fluid rates of > 500 ml h-1, is an integral part of patient temperature management strategies. Fluid warming devices using an uncoated aluminium containing heating element have been reported to liberate aluminium resulting in critical aluminium concentrations in heated fluids. We investigated saline solution (0.9%), artificially spiked with organic acids to determine the influence of fluid composition on aluminium release using the uncoated enFlow® device. Additionally, the Level1® as a high volume fluid warming device and the ThermoSens® device were investigated with artificial spiked fluid at high risk for aluminum release and a clinically used crystalloid solution.ResultsSaline solution spiked with lactate more than acetate, especially at a non neutral pH, led to high aluminium release. Next to the enFlow® device, aluminium release was observed for the Level1® device, but not for the coated ThermoSens®-device.ConclusionUncoated aluminium containing fluid warming devices lead to potentially toxic levels of aluminium in heated fluids, especially in fluids with non-neutral pH containing organic acids and their salts like balanced electrolyte solutions.

Performance analysis of solar driven combined recompression main compressor intercooling supercritical CO2 cycle and organic Rankine cycle using low GWP fluids

Current study deals with performance evaluation of the solar power tower driven recompression with main compressor intercooling (RMCIC) supercritical CO2 cycle incorporating the parallel double evaporator organic Rankine cycle (PDORC) as bottoming cycle using low global warming potential fluids to reduce the global warming and ozone depletion. Using the PDORC instead of the basic organic Rankine cycle, waste heat from the intercooler and cycle exhaust were recovered simultaneously to enhance performance of the standalone RMCIC cycle. Exergy, thermal efficiency, efficiency improvement and waste recovery ratio were considered as performance parameters. A computer program was made in engineering equation solver to simulate the model. It was concluded that by the incorporation of the PDORC thermal efficiency was improved by 7–8% at reference conditions. Maximum combined cycle's thermal and exergy efficiency were found 54.42% and 80.39% respectively of 0.95 kW/m2 of solar irradiation based on R1243zf working fluid. Among the results it was also found that maximum waste heat was recovered by the R1243zf about 54.22 % at 0.95 effectiveness of low temperature recuperator.

The hemodynamic effects of warm versus room-temperature crystalloid fluid bolus therapy in post-cardiac surgery patients.

The contribution of fluid temperature to the effect of crystalloid fluid bolus therapy (FBT) in post-cardiac surgery patients is unknown. We evaluated the hemodynamic effects of FBT with fluid warmed to 40°C (warm FBT) versus room-temperature fluid. In this single centre prospective before-and-after study, we evaluated the effects of 500 ml of warm versus room-temperature compound sodium lactate administered over <30 minutes, in 50 cardiac surgery patients admitted to ICU. We recorded hemodynamics continuous before and for 30 minutes after the first FBT. We defined CI responsiveness (CI-R) as an CI increase >15% of baseline immediately after FBT and effect dissipation if the CI returned to <5% of baseline and MAP responsiveness as >10% increase and dissipation as return to <3 mmHg of baseline. Hypotension (56%) and low CI (40%) typically triggered FBT. Temperature decreased >0.3°C in 13 (52%) patients after room-temperature FBT versus 0 (0%) after warm FBT (p < 0.01). CI and MAP responsiveness was similar (16 [64%] versus 11 [44%], p = 0.15 and 15 [60%] versus 17 [68%], p = 0.77, respectively). Among CI responders, CI increased more with room-temperature FBT (+0.6 [IQR, 0.5-1.1] versus +0.5 [IQR, 0.4-0.6] L/min/m2, p = 0.01). However, dissipation was more common after room-temperature versus warm FBT (9/16 [56%] versus 1/11 [9%], p = 0.02). In postoperative cardiac surgery patients, warm FBT preserved core temperature and induced smaller but more sustained CI increases among responders. Fluid temperature appears to impact both core temperature and the duration of CI response.

3D Basin‐Scale Groundwater Flow Modeling as a Tool for Geothermal Exploration: Application to the Geneva Basin, Switzerland‐France

AbstractSwitzerland promotes the energy transition by supporting the development of geothermal energy. We built a 3D basin‐scale fluid flow model of the Geneva Basin, France‐Switzerland, using the open‐source Matlab Reservoir Simulation Toolbox (MRST). The model is calibrated on available well and active seismic data. The goal of the numerical study is to investigate temperature and pressure distribution at the depth that could be used to identify large‐scale positive thermal anomalies. Previous and ongoing projects have assessed the geothermal potential of the region using static conductive models interpolated from bottom hole temperatures. However, a consistent basin‐scale fluid flow model of the Geneva Basin is still lacking. We perform 14 numerical models, articulated into three complementary studies to investigate how thermal properties, petrophysical parameters, and tectonic features affect fluid flow. We constrain our simulations by implementing a progressive degree of geological and petrophysical realism to study the physical processes driving fluid flow in the Geneva basin. We propose based on the simulation results a conceptual model showing that fluid flow is driven by the down‐welling of meteoric waters that cool down rocks at the edge of the Geneva Basin. In turn, this temperature drop promotes the up‐welling of warmer fluids in the center of the basin where we suggest that exploration for geothermal resources should focus. Finally, the approach presented in this study could be used for the first assessment of geothermal resources in other sedimentary basins.

Warm Fluid Infusion Is Not an Effective Primary Warming Method in Accidental Hypothermia

Warm Fluid Infusion Is Not an Effective Primary Warming Method in Accidental Hypothermia

Convective Rolls in a Compressible Fluid

Rayleigh-Bénard convection occurs between two horizontally infinite plates when the lower plate is heated with respect to the upper one. The temperature gradient between the two plates causes convective rolls to form as the warmer fluid below becomes more buoyant than the cooler fluid above it. The standard (classical) analysis uses the Boussinesq approximation, which neglects the variations of fluid density except in relation to buoyancy forces. This approximation is not accurate for some real-world applications. This project is inspired by the atmosphere, so we will consider the onset of convection in a vertically stratified layer of fluid which we model using the anelastic equations. The standard analysis is presented in many textbooks and is used as a comparison to the analysis for the compressible fluid presented here. Using linear stability analysis, we compute the critical temperature differences required to induce convection. It is not possible to find analytical solutions, and therefore, numerical methods implemented in Python using LAPACK subroutines are used. Results of the critical Rayleigh number at the half-height of the fluid for a range of plate separation distances are computed. For all the cases that are considered, the solution for the compressible problem follows the standard solution for plate separation distances smaller than some viscosity-dependent value that increases with the viscosity of the fluid. For larger d, it is observed that the stratification inhibits the onset of convection. Our solution is far more idealized than any actual convection happening in the atmosphere. However, it does demonstrate, in this context, the limits of the Boussinesq approximation.

Finite amplitude electron-acoustic waves in the electron diffusion region

The electron-acoustic solitons are studied with two temperature electrons (a hot trapped having vortex-like velocity distribution and a warm adiabatic fluid) and stationary ions. The theoretical model is based on the observations of a mixture of the hot, tenuous magnetospheric and warm, dense magnetosheath plasma particles associated with the asymmetric magnetic reconnection at the Earth’s magnetopause by Magnetospheric Multiscale (MMS). Using the reductive perturbation technique, the model supports the existence of nonlinear electron-acoustic structures derived from the mKdV-like equation. The electron-acoustic waves propagate at supersonic speeds above the electron sound speed. The results are applied to observations of electric field structures in the electron diffusion region (EDR).

Rapid Blood Transfusion: The Importance of Hemodilution and Needleless Connectors.

Introduction: Large-bore cannulas are critical to administering IV fluids and blood products during resuscitation and treatment of hemorrhage. Although catheter flow rates for crystalloid solutions are well defined, rapid administration of blood products is poorly characterized. In this in vitro study, we examined the effects of hemodilution and needleless connectors on red blood cell (RBC) flow rates.Methods: To determine RBC flow rates through large-bore cannulae, a crystalloid solution (Normosol®, Hospira, Lake Forest, IL) or RBC units were warmed and delivered under pressure (360 mmHg) using a Level 1 H-1200 Fast Flow Fluid Warmer (Smiths Medical, St. Paul, MN). Flow rates for crystalloid, packed RBCs and diluted RBCs were determined using a stopwatch. Additionally, the effect of the MaxPlus® clear needleless connector (CareFusion, San Diego, CA) was measured in all three infusion groups.Results: Flow rates for undiluted RBC units were 53% slower than crystalloid solution (220 mL/min vs. 463 mL/min; p=0.0003), however, when RBC units were diluted to a hematocrit of ~30% flow rate improved to 369 mL/min (p=0.005). The addition of the MaxPlus® needleless connector reduced flow of crystalloid solution by 47% (245 mL/min; p=0.0001), undiluted RBCs by 64% (78 mL/min; p=0.01), and diluted RBCs by 51% (180 mL/min; p=0.00003). Compared to undiluted RBC units, hemodilution increased RBC delivery rate through a MaxPlus® connector by 130% (p=0.004) and by 68% (p=0.02) when the catheter was directly connected to the Level 1 tubing (MaxPlus® excluded).Conclusion: In settings requiring rapid transfusion of RBC units, needleless connectors should not be used and hemodilution should be considered in order to decrease the time required to deliver an equivalent red cell mass.