Simulation of Ultrasonic Induced Cavitation and Acoustic Streaming in Liquid and Solidifying Aluminum

Riedel, Eric; Liepe, Martin; Scharf, Stefan

doi:10.3390/met10040476

Cited by 18 publications

(7 citation statements)

References 68 publications

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“…This implies that as the area of round tip was greater than that of flat radiator, the bubble collapse was less significant. A previous study also confirmed this fact: when a tip has smaller active area for acoustic emission, the bubble oscillation becomes more violent than that of a round tip [ 14 ]. When a spherical tip generates radial wave propagation, it induces a unique phase of acoustic streaming not seen for the flat tip, resulting in a large cavitation gas volume.…”

Section: Resultssupporting

confidence: 53%

Ultrasonic Enhancement of Chondrogenesis in Mesenchymal Stem Cells by Bolt-Clamped Langevin Transducers

Kim

Bae²,

Han³

et al. 2023

Micromachines

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We recently investigated the design and fabrication of Langevin-type transducers for therapeutic ultrasound. Effect of ultrasonic energy arising from the transducer on biological tissue was examined. In this study, the transducer was set to radiate acoustic energy to mesenchymal stem cells (MSCs) for inducing differentiation into cartilage tissue. The average chondrogenic ratio in area was 20.82% in the control group, for which no external stimulation was given. Shear stress was applied to MSCs as the contrast group, which resulted in 42.66% on average with a 25.92% minimum rate; acoustic pressure from the flat tip causing transient cavitation enhanced chondrogenesis up to 52.96%. For the round tip excited by 20 Vpp, the maximum differentiation value of 69.43% was found, since it delivered relatively high acoustic pressure to MSCs. Hence, the results from this study indicate that ultrasound pressure at the kPa level can enhance MSC chondrogenesis compared to the tens of kHz range by Langevin transducers.

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Section: Resultssupporting

confidence: 53%

Ultrasonic Enhancement of Chondrogenesis in Mesenchymal Stem Cells by Bolt-Clamped Langevin Transducers

Kim

Bae²,

Han³

et al. 2023

Micromachines

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“…Optical microscope and scanning electron microscope were used to evaluate the effect of UST on the graphite morphology as well as analyze the microstructure development for the investigated alloys. Finally, the ultrasonic streaming phenomenon in the molten iron was numerically simulated using a new computational fluid dynamic modelling (CFD) recently developed by Riedel et al 37,38 This new model helps to better understanding some of the acting mechanisms of dynamic solidification in molten metals as well as defines the optimum casting and UST parameters to achieve the finest possible structure.…”

Section: Introductionmentioning

confidence: 99%

Ultrafine Ductile and Austempered Ductile Irons by Solidification in Ultrasonic Field

Ahmed

Riedel

Kovalko³

et al. 2021

Inter Metalcast

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In this research, ultrasonic melt treatment (UST) was used to produce a new ultrafine grade of spheroidal graphite cast iron (SG iron) and austempered ductile iron (ADI) alloys. Ultrasonic treatment was numerically simulated and evaluated based on acoustic wave streaming. The simulation results revealed that the streaming of the acoustic waves propagated as a stream jet in the molten SG iron along the centerline of the ultrasonic source (sonotrode) with a maximum speed of 0.7 m/s and gradually decreased to zero at the bottom of the mold. The metallographic analysis of the newly developed SG iron alloy showed an extremely ultrafine graphite structure. The graphite nodules’ diameter ranging between 6 and 9 µm with total nodule count ranging between 900 to more than 2000 nodules per mm2, this nodule count has never been mentioned in the literature for castings of the same diameter, i.e., 40 mm. In addition, fully ferritic matrix was observed in all UST SG irons. Further austempering heat treatments were performed to produce different austempered ductile iron (ADI) grades with different ausferrite morphologies. The dilatometry studies for the developed ADI alloys showed that the time required for the completion of the ausferrite formation in UST alloys was four times shorter than that required for statically solidified SG irons. SEM micrographs for the ADI alloys showed an extremely fine and short ausferrite structure together with small austenite blocks in the matrix. A dual-phase intercritically austempered ductile iron (IADI) alloy was also produced by applying partial austenitization heat treatment in the intercritical temperature range, where austenite + ferrite + graphite phases coexist. In dual-phase IADI alloy, it was established that introducing free ferrite in the matrix would provide additional refinement for the ausferrite.

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“…The increase in a surface roughness of the first part could be caused by a spatter due to significant vibration, or by the difference in the cooling rate of the lowest and the highest layers [31]. This difference comes from the fact that layers, larger affected by ultrasonic vibration, undergo more intense stirring provided by cavitation and acoustic flow effects [67] in a melt pool. The cavitation effect is associated with nonlinearly expanding, contracting, oscillating, shrinking, and collapsing cavitation bubbles in liquid under alternating negative and positive pressure.…”

Section: Ultrasonic-assisted Ded Processmentioning

confidence: 99%

Perspective Chapter: Direct Energy Deposition of Cu-Fe System Functionally Graded Materials – Miscibility Aspects, Cracking Sources, and Methods of Assisted Manufacturing

Makarenko¹,

Dubinin²,

Shishkovsky³

2022

Advanced Additive Manufacturing

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Direct energy deposition is a reliable additive manufacturing method of producing components with highly sophisticated geometry from a single material or combination of different materials with high manufacturing freedom and efficiency. The assembly operations are not required after the direct energy deposition: such complex parts as a rocket combustion chamber, a nuclear reactor element, a heat exchanger, and so on, could be fabricated layer-by-layer during one technological step. Promising applications are associated with Cu-Fe system laser deposited functionally graded components, which allow combining good oxidation resistivity, antifrictionality, thermal, and electrical conductivity of copper with mechanical strength, processability, and corrosion resistance of stainless steel. The main issue, which appears in the case of laser deposition of such materials, is internal stresses caused by significant inequality of physical properties of copper/bronze and steel, their limited miscibility, forming of brittle phases at the interface, and complexity of variation of mechanical and physical properties of the resulted alloy. The mentioned factors could cause various cracking in resulted parts. Specific techniques such as ultrasonic assistance, implementation of the external magnetic field, and post-treatment (hot isostatic pressing, machining), could be suggested to improve the quality of laser deposited Cu-Fe system functionally graded materials.

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Simulation of Ultrasonic Induced Cavitation and Acoustic Streaming in Liquid and Solidifying Aluminum

Cited by 18 publications

References 68 publications

Ultrasonic Enhancement of Chondrogenesis in Mesenchymal Stem Cells by Bolt-Clamped Langevin Transducers

Ultrasonic Enhancement of Chondrogenesis in Mesenchymal Stem Cells by Bolt-Clamped Langevin Transducers

Ultrafine Ductile and Austempered Ductile Irons by Solidification in Ultrasonic Field

Perspective Chapter: Direct Energy Deposition of Cu-Fe System Functionally Graded Materials – Miscibility Aspects, Cracking Sources, and Methods of Assisted Manufacturing

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