Axial Circulation Research Articles

The numerical simulation investigates the influence of agitator parameters on particle suspension characteristics

This study investigates the effect of different agitator parameters in a baffleless stirred reactor on solid particle suspension during quaternary ammonium chitosan synthesis. Computational Fluid Dynamics (CFD) simulations investigate different agitator configurations, including blade diameter, rotational speed, and bottom clearance, to optimize chitosan particle distribution. Reducing the bottom clearance reduces particle accumulation, but can create stagnant zones that may disrupt fluid flow. Increasing the rotational speed improves particle distribution until a saturation point is reached. Increasing paddle diameter improves axial fluid circulation. Optimal settings for the vane size of a 180 mm reactor vessel are identified as 0.45 times the diameter, with a speed of 350 rpm, and a bottom clearance of 0.25 times the diameter. These simulations provide critical insight into the suspension of solid particles in baffleless stirred reactors and provide valuable guidance for optimizing stirrer parameters.

Current aspects of the treatment of combat surgical trauma

Objective. The history of providing assistance to victims with gunshot wounds dates back more than one century, but nevertheless surgical treatment of gunshot wounds is still relevant to this day. High-quality primary surgical treatment of a gunshot wound is the key to a speedy recovery of the patient (N.I. Pirogov). The pathogenesis of gunshot wounds determines the specific tactics of surgical treatment. Gunshot wounds are zonal in nature. According to the results of morphological studies, it can be concluded that a significant part of the changes in the zone of molecular concussion of the wound canal are reversible, and the complexity of pathogenesis and the lack of reliable criteria for assessing the condition of tissues does not exclude the possibility of leaving areas with reduced viability in the wound after treatment. For maximum effect during surgical treatment of gunshot wounds, non-viable tissues should be removed with minimal damage to viable ones. To meet these requirements, it is often impossible to visually assess the boundary between damaged and parabiotic tissues objectively intraoperatively. The use of modern physical methods of wound wrapping and preparing them for plastic closure, such as low-frequency ultrasound, hydrosurgical methods and VAC therapy allows you to radically clean the wound surface with minimal damage to viable tissues and perform plastic closure operations on soft tissue defects at an early date.Purpose of a study: to improve the methods of primary surgical treatment in patients with combat surgical trauma using low-frequency ultrasound.Material and methods. Our study is based on the analysis of the treatment results of 93 patients aged 10 and 70 years old. All patients had combat surgical trauma of various etiology and localization. Of these, 36 (38.7%) patients in main group underwent ultrasound cavitation of the wound canal and wound defects during primary surgical treatment (PST), followed by primary or primary delayed plastic surgery within a period not exceeding 48 hours after PST. Methods of plastic wound closure were both flaps with axial circulation and autodermotransplantation. In the remaining 57 (61.3%) patients of comparison group, primary surgical treatment was not performed, or was performed at the stages of evacuation, with further conservative treatment. Upon admission to the clinic, he underwent secondary surgical treatment, opening of purulent lumps, as well as staged necrectomies, while wound plastic surgery was performed after wound cleansing and was mainly represented by autodermotransplantation.Results. It was revealed that in the main group, the treatment time of patients in the main group was reduced by 2 times compared with the comparison group (16.3 and 34.2 bed days, respectively). The effectiveness of engraftment of autodermotransplants was evaluated according to V.I. Petrov's scheme. Lysis of autodermotransplants was noted 1.9 times less frequently in the main study group. It was also noted that there were no purulent complications in main group, unlike comparison group – 20.6%, the number of marginal necrosis was 2.6% in main group and 22.4% – in comparison group, lysis of autodermotransplanates in main group was 7.8%, in comparison group – 13.8%.Conclusion. This study allows us to conclude that the advantage of using ultrasonic cavitation during the usual surgical treatment of gunshot wounds followed by primary or primary delayed plastic surgery.

Modification of impeller blades for the efficient mixing of particulate suspensions in a stirred tank

The fractal arrangement of perforated holes were introduced in the impeller blades for the suspension of solid particles in a stirred tank. The mixing characteristics of solid-liquid two phases in a stirred tank with a fractal arrangement perforated impeller (FAP impeller) were investigated. Results indicated that incorporating fractal arranged perforated holes in the impeller blades resulted in a reduction in power consumption (P) compared to conventional designs under the same agitation speed. Moreover, a rise in the iteration quantity of fractal arranged perforated holes in impeller blades resulted in higher power consumption and power number, but still lower than those observed with conventional designs. FAP impeller enhanced turbulent intensity, increased shear effect on the fluid, minimized trailing vortex dimension behind the impeller blades, and promoted the axial circulation of solid particles, ultimately leading to the better suspension quality of solid particles compared to pitched blade impeller at the constant P. The above phenomena became increasingly evident as the iteration number in the fractal arranged perforated holes in the FAP impeller blades increased.

Research Progress of Enhanced Thermal Evacuation and Cooling Technology for High-Speed Motors

In high-speed motors, there is a huge amount of heat generation from core and winding losses, which may result in thermal failures or motor performance deterioration. In the prevention of heat accumulation, efficient cooling technology is critical for smooth and reliable motor movement. This paper summarizes the diverse application of high-speed motor and thermal requirements, such as in electrical devices, turbo-machinery, and high-precision machine tools. Three paths of case convection—cooling, internal ventilation cooling and spindle core cooling—are analyzed. Methods for configuring thermal resistance and improving cooling efficiency are summarized. Among them, coolant flow characteristics and flow channel shapes, gas supply ventilation systems, and methods to reduce air resistance, as well as axial cooling and integrated heat pipe structures, are extensively investigated. Finally, the development prospects of high-speed motor cooling are also forecasted. At present, the primary research directions are to reduce the heat generated by the heat source, utilize the latent heat of the coolant, optimize the cooling flow path of the shell, design an axial air-cooling circulation system, and enhance the heat dissipation of the spindle.

Indoor Particulate Matter Transfer in CNC Machining Workshop and The Influence of Ventilation Strategies—A Case Study

Particulate matter in Computer Numerical Control (CNC) machining workshop is harmful to workers’ health. This paper studies particulate matter transfer and the performance of various ventilation strategies in a CNC machining workshop. To obtain the boundary condition of the particle field, instruments were installed to obtain the particle size attenuation characteristics and source strength, respectively. The results show that the 99% cumulative mass concentration of particles is distributed within 1.5 μm, and the release rate of particles from the full enclosure. Next, the indoor flow field and particle field were simulated by numerical simulation with the measured boundary conditions. The working area’s age of air, particle concentration, and ventilation efficiency were compared between four displacement ventilation methods and one mixed ventilation method. The results show that the working area’s mean particle concentration and ventilation efficiency under longitudinal displacement ventilation is better than other methods. At the same time, the mean age of air is slightly worse. In addition, mixed ventilation can obtain lower mean age of air, but the particle concentration is higher in the working area. The bilateral longitudinal ventilation can be improved by placing axial circulation fans with vertical upward outlets in the center of the workshop.

Hydrodynamic Characteristics of a Stirred Tank with Self‐Priming Jet Impeller

AbstractMultiple inclined hollow pipes were combined to form a self‐priming jet (SPJ) impeller. The hydrodynamic and mixing characteristics in the tank were studied by numerical simulation. The feasibility of the numerical simulation model was verified by particle distribution experiments. The results showed that the turbulence intensity and vorticity were affected by the installation height and diameter of the impeller; the mixing performance was improved with increasing diameter and installation angle. The study on the enhanced mixing mechanism showed that the self‐priming was generated in the lower part of the impeller, the flow was accelerated in the empty pipe, and the jet was generated in the upper part of the impeller. Self‐priming and jet caused multiple axial internal circulation flows in the SPJ tank.

Investigation of the Intensified Chaotic Mixing and Flow Structures Evolution Mechanism in Stirred Reactor with Torsional Rigid-Flexible Impeller

This investigation addresses the development of a Möbius strip with torsional structure as the flexible connection pieces for rigid-flexible impellers, enhancing the macroinstability of the flow field structure, the fluid transfer efficiency, and the chaotic mixing degree in the stirred tank. The effects of intrinsic parameters, including the impeller types and length and width of the flexible connection piece among impellers on the laminar flow field were explored. In addition, the chaotic characteristic parameters, helicity distribution, vorticity distribution, flow field structure evolution, power consumption, and fluid velocity of different rigid-flexible impeller systems were investigated as well. The experiment and computational fluid dynamics calculations demonstrated that the DRFMSC-PBDT system with torsional structure has better mixing characteristics at a lower level for power consumption, being clearly superior to DRFC-PBDT and DRFTSC-PBDT in the LLE and NTm values. The torsional structure of the Möbius strip could facilitate strengthening to form the axial circulation of the flow field, decreasing mass transfer resistance and destroying the stability of the flow field structure while contributing to improving the mixing efficiency of the system. In addition, the enhanced superior proportion of the stagnant zone and the mixing zone is also attributed to the increased secondary flow, as well as the generated perturbation wave with larger amplitude and smaller frequency, which are responsible for mixing in laminar flows.

Types of surgical approaches in locally advanced forms of basal cell carcinoma of the scalp in elderly patients

Background. Basal cell cancer is the most common type of skin cancer in fair-skinned adults older than 50 years. The incidence rate of this disease is growing around the world. Basal cell carcinomas (BCC) are heterogeneous: from superficial or nodular lesions with benign prognosis to large lesions which are very difficult to cure. The prognosis of treatment is connected with the risk of recurrence of basal cell cancer or its local destructive ability. Hedgehog pathway activation is a distinctive molecular event in these tumors, which has allowed Hedgehog inhibitors for lesions that are difficult to cure to be developed, and which are also beyond the reach of surgical treatment or radiation therapy. Immunotherapy may be offered for the treatment of tumors with a high mutational load which leads to tumor resistance to Hedgehog inhibitors. Surgical intervention is a standard treatment method for most BCCs because it allows excision margins to be controlled and it shows a low risk of recurrence. The issue of removal of locally advanced forms with simultaneous reparative stage in elderly patients remains challenging.
 Purpose – to prove the high effectiveness of the surgical approach with simultaneous plastic surgery in locally advanced forms of BCC of the scalp in elderly patients.
 Materials and methods. Clinical observation of female patient A., 87 years old, who was receiving treatment in the Department of Surgical Oncology regarding multiple advanced BCC of facial skin, and patient V., 91 years old, who was undergoing treatment in the Department of Surgical Oncology regarding advanced basal cell skin carcinoma of the left pinna. Observation and treatment were performed in the State Organization «Grigoriev Institute for Medical Radiology and Oncology of the National Academy of Medical Sciences of Ukraine».
 Results. Clinical cases of locally advanced basal cell skin cancer in 2 elderly patients (87 and 91 years old) are presented. The effectiveness of the surgical approach with broad excision of the tumor and simultaneous reparative stage has been proven: in one case – a free split-skin autoplastic graft, in the other one – a full-thickness musculo-subcutaneous flap with axial blood circulation. In both cases there was no rejection of transplants; the scalp defects were completely covered, and a good cosmetic appearance was successfully achieved. In both cases, there were no significant complications observed. These examples have proven that the patients’ age of more than 90 years is not a counterindication to broad resections with simultaneous reparative stage in locally advanced BCC of the scalp.
 Conclusions. Thus, modern methods of diagnostics and treatment of BCC allow the disease to be controlled in most cases. It is also possible to cure locally advanced BCCs in patients older than 85 years surgically with a simultaneous reconstructive stage, given the reasonable selection of the patients.

Design of impeller blades for intensification on fluid mixing process in a stirred tank

BackgroundMany studies reported that the nonlinear geometry could create a longer turbulence production region and higher turbulence intensities compared with conventional geometry. The self-similarity impeller based on Hibert curves was introduced to intensify the fluid mixing process in this work. MethodsThe mixing performance of Rushton turbine (RT) impeller and self-similarity impeller were evaluated using experimental analyzes and computational fluid dynamics (CFD) with detached eddy simulation (DES) approach. The chaotic mixing characteristics, mixing time, power consumption, trailing vortices structures, turbulence intensity, turbulent kinetic energy dissipation rate and velocity magnitude distribution were investigated. Significant findingsResults showed that self-similarity impeller can effectively increase the largest Lyapunov exponent (LLE) and multiscale entropy (MSE) of mixing system, shorten the fluid mixing time and decrease the mixing number (η) compared with RT impeller under the constant power consumption, and an improvement was achieved in mixing efficiency with the increase of self-similar iteration number of self-similarity impeller. Meanwhile, the reductions in the power number (Np) of 34.6% with self-similarity 1 impeller and 51.9% with self-similarity 2 impeller were achieved in a wide Re range compared with RT impeller. Two large recirculation zones and trailing vortices were easy to form at the suction side of rectangular impeller blade, which can be destroyed and decomposed into smaller ones through the jet flows produced by the concave-convex structure of self-similarity impeller. In addition, self-similarity impeller can improve the uniformity of fluid turbulence intensity, enhance the turbulent kinetic energy dissipation rate and increase the axial circulation capacity in the stirred tank, and increasingly so with the self-similar iteration number.

Pilot Study of Additive Effect of "Offloading Ilizarov Frame" To Reduce "Reverse Sural Flap" Surgery Complications: A Clinical Trial.

A reverse sural flap is an available surgical technique because it provides robust axial blood circulation to flaps with a substantially larger surface area. We aimed to assess Ilizarov frames outcome after reverse sural flaps among patients with traumatic injuries to the distal portion of the leg. Patients with traumatic distal injury of leg in Shoha-e Tajrish Hospital in 2022-2021 were recruited and treated with reverse sural flaps. Interventional group was followed by Ilizarov frames application (group A). For the second group, just conventional dressings and proper positioning were done after surgery (group B). Between the two groups, the duration of surgery, the degree of flap swelling, the time from surgery to discharge and flap failure, surgical site infection, deep vein thrombosis (DVT), and other complications were compared using SPSS 25 software. Of 26 recruited patients, twenty consented to participate in this study. The average time from initial injury to reconstruction surgery, the mean duration of surgery, the mean time from surgery to discharge and the degree of swelling of the flap was compared between these two groups. The results showed better outcome in Ilizarov group, but the flap swelling grade was the only statistically significant factor between groups (P value= 0.03). The use of "offloading Ilizarov frames" to protect reverse sural flaps resulted in a considerable reduction in the flap swelling. It is a safe, quick, easy, and effective technique.

Heat Transfer Characteristics of Hot Slag Modification in a Mechanically Agitated Slag Pot

Hot slag modification is an energy‐saving technology to promote the reuse of metallurgical slag. In order to improve the temperature distribution uniformity of hot slag and prevent the solidification of hot slag surface during modification, two different structures of slag pots are studied by numerical simulation in this paper, one is using mechanical stirring, and the other one did not. The heat transfer characteristics of the hot slag are investigated by considering the natural convection. In addition, the temperature renewal mechanism of the hot slag surface is discussed. The effect of mechanical stirring on the crusting time of hot slag surface is further studied, and the appropriate modification time is determined. The results show that mechanical stirring can improve the temperature distribution uniformity of hot slag. After mechanical stirring for 2400 s, the surface temperature of hot slag is about 1617 K, which is significantly higher than that without mechanical stirring. The temperature renewal mechanism of the hot slag surface depends on the turbulent kinetic energy of the surface and the axial circulation velocity. The solidification time of the hot slag surface is prolonged by mechanical stirring, and the appropriate modification time is within 2470 s.

Fully Three-Dimensional Hemodynamic Characterization of Altered Blood Flow in Bicuspid Aortic Valve Patients With Respect to Aortic Dilatation: A Finite Element Approach.

Background and PurposePrognostic models based on cardiovascular hemodynamic parameters may bring new information for an early assessment of patients with bicuspid aortic valve (BAV), playing a key role in reducing the long-term risk of cardiovascular events. This work quantifies several three-dimensional hemodynamic parameters in different patients with BAV and ranks their relationships with aortic diameter.Materials and MethodsUsing 4D-flow CMR data of 74 patients with BAV (49 right-left and 25 right-non-coronary) and 48 healthy volunteers, aortic 3D maps of seventeen 17 different hemodynamic parameters were quantified along the thoracic aorta. Patients with BAV were divided into two morphotype categories, BAV-Non-AAoD (where we include 18 non-dilated patients and 7 root-dilated patients) and BAV-AAoD (where we include the 49 patients with dilatation of the ascending aorta). Differences between volunteers and patients were evaluated using MANOVA with Pillai's trace statistic, Mann–Whitney U test, ROC curves, and minimum redundancy maximum relevance algorithm. Spearman's correlation was used to correlate the dilation with each hemodynamic parameter.ResultsThe flow eccentricity, backward velocity, velocity angle, regurgitation fraction, circumferential wall shear stress, axial vorticity, and axial circulation allowed to discriminate between volunteers and patients with BAV, even in the absence of dilation. In patients with BAV, the diameter presented a strong correlation (> |+/−0.7|) with the forward velocity and velocity angle, and a good correlation (> |+/−0.5|) with regurgitation fraction, wall shear stress, wall shear stress axial, and vorticity, also for morphotypes and phenotypes, some of them are correlated with the diameter. The velocity angle proved to be an excellent biomarker in the differentiation between volunteers and patients with BAV, BAV morphotypes, and BAV phenotypes, with an area under the curve bigger than 0.90, and higher predictor important scores.ConclusionsThrough the application of a novel 3D quantification method, hemodynamic parameters related to flow direction, such as flow eccentricity, velocity angle, and regurgitation fraction, presented the best relationships with a local diameter and effectively differentiated patients with BAV from healthy volunteers.

Floating particles mixing characteristics in an eccentric stirred tank coupled with dislocated fractal impellers

Abstract The mixing characteristics of floating particle dispersion process in an eccentric stirred tank with dislocated fractal impellers were investigated using computational fluid dynamics (CFD) and experimental analyses. Solid concentration distribution, axial solid concentration profile, cloud height, solid integrated velocity, power consumption and just drawdown speed were investigated. Results showed that dislocated fractal impeller can enhance solid integrated velocity and fluid turbulent fluctuation intensity compared with dislocated pitched blade impeller, and eccentric agitation coupled with dislocated fractal impeller could destroy the typical circulation loops and symmetric flow field and improve the axial circulation efficiency of floating particles on the basis of dislocated fractal impeller. Eccentric agitation coupled with dislocated fractal impeller could further enhance the floating particle dispersion homogeneity (MI) and decrease the just drawdown speed (N jd) on the basis of dislocated fractal impeller and dislocated pitched blade impeller at the specific power consumption. Meanwhile, eccentric ratio of 0.3 or 0.4 was optimal for the floating particle mixing process in this work.

Лечение последствий ранений голени: продолжение развития технологии Илизарова

Introduction Severe open injuries and wounds of the tibia refer to the topical problem of traumatology due to the difficulties in the functional restoration of the segment when there is a bone and soft tissues defect. Material and method The treatment of 11 patients with soft tissue and tibial defects was analyzed. At the time of reconstruction, the age of male patients ranged from 20 to 52 years (mean age 34.2 ± 3.2 years). Gunshot wounds of tibia occurred in 7 injured and tibial injury was observed in 4 cases. Segmental defects of the tibia ranged from 6 cm to 18 cm, mean 12.6 ± 4.4 cm, myocutaneous defects ranged from 20 cm2 to 112 cm2, mean 74.4 ± 22.4 cm2. Results In seven cases, the wounds healed by primary intention, the signs of infection and marginal necrosis of the soft tissue component of the flap were observed in 4 (36.4 %) cases and were addressed conservatively (dressings and debridement), but in one case, necrosis was excised (on day 21) and autodermoplasty was performed using split skin graft. We had no problems with the transport (distraction) of bone regenerates, since the rib cage of the flaps protected the soft tissues and the vascular pedicle of the flap, despite the early start of distraction (mean period 7.3 ± 2.1 days) and the length of treatment, when averaged, was 163.2 ± 8.7 days. Support function was restored in all patients and the functional results were satisfactory. Discussion The combination of Ilizarov distraction osteogenesisand soft tissue reconstruction using free vascularized flap grafting makes it possible to invalidate the short-comings of both, i.e. to lighten up the bone transfer, to avoid damage to the scarred skin of the anterio-medial surface of tibia and to preserve the axial circulation of the graft. The inclusion of a rib fragment provided the required conditions for application the Ilizarov distraction method. The rib, not being a supportive bone tissue, protected the soft tissue component of the flap and its vascular pedicle from deformity and participated in the formation of callus. Conclusions Plastic filling in the extensive tibial defects using free vascularized myocutaneous flap with rib fragments and Ilizarov distraction osteogenesis provides favorable conditions for acute surgical intervention allowing to save the limb, restore the support ability and return the patients to work.

Geometrical configuration of hydrocyclone for improving the separation performance

The inherent defect of particle misplacement in traditional hydrocyclones is the main reason for the deterioration of separation accuracy and has obtained wide attentions. This paper presents three novel hydrocyclones based on the traditional cylindrical-conical type and cylindrical type. The effect of the hydrocyclone structure on the flow field characteristics and separation performance is investigated by a validated two fluid model. The numerical results show that a higher turbulence intensity deteriorates the separation performance of CCB type (cylindrical-conical-flat bottom type) and C type (cylindrical type), while a greater tangential velocity and velocity gradient improve the separation accuracy of MS type (multi-stage cylindrical type). Hydrocyclones with a flat-bottom structure reduces the misplaced fine particles due to the effect of the internal swirling flow and the axial circulation flow in the spigot. The MS type has the lowest imperfection value and the cut size of 76.5 μm implying a sharpness separation sharpness and an appropriate separation result. CC type has the minimum cut size of 62.21 μm, while the maximum cut size of 120.68 μm for C type.

Three-dimensional modeling of the flow around the gas scoop under optimal working regime of the Iguassu gas centrifuge at the hyper fast rotation

The problem of the gas withdrawal from an Iguassu gas centrifuge (GC) at the speed of rotation, over 1000 m/s is considered. We focus our attention on the problem of achieving of optimal waste flow and friction power of the gas scoop simultaneously. Calculations were carried out in a three-dimensional approximation for supersonic flow of UF 6 around a stationary gas scoop taken as a Pitot tube with a diameter of 2 mm. Attempts to achieve the optimal working regime of GC for the selected particular gas scoop were not successful. On the basis of this results we conclude that the optimal gas withdrawal and creation of the optimal axial circulation can be problematic for the hyper-speed gas centrifuges.

A hydrogen peroxide electric pump for throttleable hybrid rocket motor

The prosperity of commercial space drives the development of advanced rocket engines and propellants. Extensive research has shown that the electric pump feed system has good prospects in liquid rocket engine for its simplicity and controllability. However, the combination of electric pump feed system and hybrid motor has not been studied adequately. In this paper, design of a hydrogen peroxide electric pump for throttleable hybrid rocket motor is completed. In the scheme, a centrifugal pump is driven by a permanent magnet synchronous motor rated 75 kW and 36000 rpm with a sensor-less controller. The design of an axial backflow circulation is adopted in consideration of bearing lubrication and heat dissipation. The results of simulation and experiments show that the head and mass flow rate of the electric pump meets the requirement of target hybrid motor and the total efficiency reaches 58.6% under rated condition. The heat protection design is effective for the temperature rise during the operation is safe for hydrogen peroxide. Nonetheless, the acceleration of the motor still needs improvement. The results of this paper provide experimental verification of electric pump feed system for hybrid rocket motor.

Hot Slag Modification with Mechanical Stirring: Motion and Dispersion Characteristic of Modifier Particle

To improve the modification efficiency and effect of hot slag with mechanical stirring, the motion and dispersion characteristic of modifier particles with stirring time are investigated by numerical simulation, and the entrainment mechanism of particle with mechanical stirring was discussed. In addition, a quantitative index of particle dispersion characteristic suitable for discrete particle simulation is proposed and the effects of stirring speed and impeller structure on the dispersion of modifier particle were also elucidated. The results show that four circulation streams on each side of cross-shaped impeller which are beneficial to complete mixing between modifier particles and hot slag. The dispersion of modifier particles depends on the axial circulation velocity and turbulent kinetic energy of hot slag surface. A dynamic steady state of particle motion in each region can be obtained within 8 s by mechanical stirring. The stirring speed of 60 rpm by cross-shaped impeller are more conducive to hot slag modification.

Impact of Electroosmosis and Wall Properties in Modelling Peristaltic Mechanism of a Jeffrey Liquid through a Microchannel with Variable Fluid Properties

The current work emphasizes the modelling of the electroosmosis-modulated peristaltic flow of Jeffery liquid. Such flows emerge in understanding the movement of biological fluids in a microchannel, such as in targeted drug delivery and blood flow through micro arteries. The non-Newtonian fluid flows inside a non-uniform cross-section and an inclined microchannel. The effects of wall properties and variable fluid properties are considered. The long wavelength and small Re number approximations are assumed to simplify the governing equations. Debye-Hückel linearization is also utilized. The nonlinear governing equations are solved by utilizing the perturbation technique. MATLAB is used for the solution, velocity, temperature, skin friction, coefficient heat transport, concentration, shear wood number, and streamlines expressions. The obtained result in optimal electroosmotic velocity (or Helmholtz-Smoluchowski velocity) increases from −1 to 6; the axial circulation has substantial momentum. For larger optimal electroosmotic velocity, a subsequent boost in an axial electric field causes a significant deceleration. Further, the study helps biomedical engineers to create biomicrofluidics devices that may aid in carrying biological fluids.

1529 Management of A Rare Case of Bilateral Persistent Sciatic Artery Aneurysms Causing Critical Limb Ischaemia With Staged Embolisation And Femoropopliteal Bypass: A Case Report

Abstract Introduction Bilateral persistent sciatic arteries (PSA) are rare with an incidence of 0.001%. They represent a persistence of the embryonic axial limb circulation via the internal iliac artery. Normally the PSA involutes and is replaced by the superficial femoral artery (SFA). Failure of regression leads to a PSA with varying configurations. Up to 50% of PSAs are aneurysmal and may present with rupture or acute/chronic ischaemia, typically at 40-50 years old. Case Report A 74-year-old female presented with limb threatening ischaemia manifesting with rest pain, sensory deficit and early tissue loss (Rutherford IIb). She had a left femoral pulse but absent pulses distally. Pedal pulses were noted on the contralateral limb. CT angiogram revealed bilateral complete PSAs with incomplete hypoplastic SFAs (Pillet-Gauffre 2a). Both PSAs were aneurysmal; the left PSA was acutely occluded distal to the aneurysm. She underwent staged intervention with percutaneous embolisation of the left PSA, followed by femoropopliteal bypass. She was discharged six days later with good symptomatic relief at one month follow up. We are planning to treat the contralateral limb in a similar manner electively in case complications occur. Conclusions PSAs are commonly associated with limb threatening complications but due to their rarity there are limited reports on the management of this condition. Here we can report a good outcome in a late presentation using staged embolisation with open reconstruction.