RIIST, resonance induced instability for surface tension measurement, a new technique with experiments in microgravity
Year: 2026
Type: article
Abstract: This study reports a new method of analysis to measure the surface tension of high melt-temperature liquid metals using levitation in microgravity. The method, which leads to a self-consistent benchmarking technique to determine surface tension, requires forced oscillations of a levitated drop until the drop responds by deforming at a target mode, say the first fundamental mode of the natural frequency of the drop. Decomposition of the drop shape into Legendre modes, followed by time-domain analysis, reveals that the response to a target-mode forcing is composed of multiple modes that oscillate at frequencies, commensurate with the natural frequencies of those modes. We refer to the multiple modes that emanate from the target mode forcing as subordinate or ancillary modes. This then means that multiple modal shapes constituting the deforming drop's response co-exist. It is found that the ratios of the experimentally determined ancillary modal frequencies correlate well with the theoretical ratios predicted by the Rayleigh formula, thereby providing a self-consistent benchmark method for surface tension determination for any given sample, regardless of its composition. Validation of this method has been performed using experiments on the Electrostatic Levitation Furnace (ELF) in the KIBO module aboard the International Space Station (ISS) demonstrating accuracy and precision.
Source: npj Microgravity
Authors: Thomas Corbin, Jason Livesay, Takehiko Ishikawa, Chihiro Koyama, Michael SanSoucie, Brandon Phillips, Ranga Narayanan
Language: English
Subfield: Computational Mechanics
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,690
Awards: A NOVEL METHOD USING AN ELECTROSTATIC LEVITATOR (EL) IS PROPOSED TO DETERMINE THE INTERFACIAL TENSION (IFT) OF LIQUID/GAS SYSTEMS. THIS KEY THERMOPHYSICAL PROPERTY IS OF INTEREST FOR MATERIALS PROCESSING AND IN WELDING OPERATIONS IN SPACE AND ON GROUND. THE NOVEL METHOD FOR MEASUREMENT OF IFT PROPOSED INVOLVES THE USE OF ELECTROSTATICALLY FORCED FARADAY INSTABILITY. IN THIS METHOD AN OSCILLATORY ELECTROSTATIC FORCING IS APPLIED TO A LIQUID SYSTEM RESULTING IN SUDDEN PATTERN FORMATION AT THE INTERFACE I.E. AN INSTABILITY IS CAUSED. THE "INSTABILITY" IS A RESULT OF RESONANCE BETWEEN THE IMPOSED FORCING FREQUENCY AND THE NATURAL FREQUENCY OF THE SYSTEM. THE CRITICAL AMPLITUDE AND MODE SHAPES ARE PREDICTABLE FROM LINEAR STABILITY THEORY AND AGREE SUPERBLY WITH EXPERIMENTS. THE MEASUREMENT OF IFT DIRECTLY ALIGNS WITH THE GOALS OF THE THERMOPHYSICAL PROPERTY MEASUREMENT EMPHASIS OF THE CURRENT NRA. FARADAY EXPERIMENTS BY THIS TEAM USING MECHANICAL FORCING HAVE SHOWN EXCELLENT AGREEMENT BETWEEN THEORY AND EXPERIMENTAL RESULTS. HOWEVER IN THE CASE OF MECHANICAL FORCING THE FORCE OF GRAVITY OVERWHELMS THE EFFECTS OF IFT ON THE SYSTEM STABILITY AND THEREFORE IT IS ALMOST IMPOSSIBLE TO DETERMINE THE IFT WITH ACCURACY. ELECTROSTATIC FORCING COUNTERS GRAVITY ALLOWING THE EFFECTS OF IFT TO PLAY A SIGNIFICANT ROLE IN THE ULTIMATE DETERMINATION OF THE SYSTEM STABILITY. ACCORDINGLY EXPERIMENTALLY MAPPED STABILITY CURVES CAN BE FIT ACCURATELY WITH THEORETICAL CURVES ALLOWING FOR THE DETERMINATION OF THE IFT WITH GREAT ACCURACY. THE PROPOSING TEAM HAS SUCCESSFULLY USED ELECTROSTATIC FORCING IN GROUND EQUIPMENT TO SHOW THAT FARADAY WAVES CAN BE OBTAINED AS PER THEORETICAL PREDICTIONS. THE CURRENT STATE OF THE ART USES AN OPEN CONTAINER GEOMETRY TO HOLD THE LIQUID. HOWEVER A LEVITATED SPHERE MAY ALSO BE USED AND OUR PROPOSAL NECESSARILY INCLUDES THIS METHOD. WE THEREFORE PROPOSE A PROJECT WITH TWO NEW ASPECTS. IN THE FIRST STAGE OF THE RESEARCH WE PROPOSE TO USE GROUND-BASED FACILITIES AT JAXA AND NASA MARSHALL TO ACCURATELY OBTAIN THE IFT FOR LIQUIDS USING ELECTROSTATIC FARADAY FORCING IN OPEN CONTAINERS AS WELL AS IN LEVITATED DROPS. IN THE SECOND STAGE OF THE RESEARCH WE WILL PERFORM FLIGHT EXPERIMENTS USING THE ELF IN ISS TO OBTAIN THE THRESHOLD FOR INSTABILITY AND DETERMINE THE IFT OF THESE SYSTEMS. IN SUMMARY THE RESEARCH ALLOWS AN ALTERNATE NEW METHOD VIZ. FARADAY INSTABILITY FOR THE DETERMINATION OF INTERFACIAL TENSION. USING ELECTROSTATIC FORCING INSTABILITY WILL PERMIT AN INDEPENDENT CONFIRMATION OF MEASUREMENTS OBTAINED BY THE SINGLE-PULSE OSCILLATINGDROP TECHNIQUE WHERE DECAY RATES ARE MEASURED AND RELATED TO INTERFACIAL TENSION AND VISCOSITY. GROUND-BASED RESEARCH USING THE ELECTROSTATIC LEVITATOR AVAILABLE AT THE NASA MSFC AND JAXA AND SPACE EXPERIMENTS ON ELF IN THE ISS WILL PROVIDE ACCURATE DATA. IN ADDITION TO BEING AN ALTERNATIVE METHOD FOR IFT MEASUREMENT THE PROPOSED TECHNIQUE ALSO HAS VERSATILITY AS A POTENTIAL MEANS IN MEASURING INTERFACIAL TENSION FOR HIGH VISCOSITY MATERIALS AND TWO-LIQUID INTERFACIAL TENSION ON GROUND AS WELL AS IN SPACE. THE PROPOSING TEAM HAS RECENTLY COLLABORATED SUCCESSFULLY WITH JAXA AND HAS CONDUCTED EXPERIMENTS TO STUDY THE FEASIBILITY OF ELECTROSTATIC FARADAY INSTABILITY. THESE RESULTS FORM THE BASIS FOR THE CURRENT PROPOSAL., ISS: Fluid Resonance Instability for Enhancing Heat Transfer, ISS: Gravitational Effects on the Faraday Instability
OpenAlex ID: W7150820287