Podcasts about mass transfer

Chair Professor and Dean of Research & Innovation joins host Sue Rocco for a conversation about why she wanted to leave her rural town in the south of France, how she discovered her calling in research, and how she dealt with gender bias that she faced in school and among her peers.Sylvie Lorente, Associate Dean for Research & Innovation in the College of Engineering at Villanova University, shared the story behind her title with us on September 6, 2023.Sylvie is also a Professor (Exceptional Class) at the National Institute of Applied Sciences (INSA), University of Toulouse, France. In 2019, she joined Villanova University where she holds the position of College of Engineering Chair Professor in the department of Mechanical Engineering.She was appointed Hung Hing-Ying Distinguished Visiting Professorship in Science and Technology at Hong Kong University (Hong Kong) in 2017. Sylvie Lorente is also an Extraordinary Professor at the University of Pretoria (South Africa), and an Adjunct Professor at Duke University, USA. She is a member of the Academia Europaea.She is editor of the International Communications in Heat and Mass Transfer and a member of several other editorial boards. Sylvie Lorente has a passion for flow architectures and works on thermal design, energy storage, vascularized structures, porous media, biological flow networks, urban design, and organisations. Together with her group, she uncovers the engineered and biological hierarchical flow pathways that endow complex systems with efficient properties and behaviors. She is the author of 7 books, 10 book chapters, and 200+ peer-reviewed international journal papers. She is listed amongst the 2% most cited scientists worldwide.Support this podcast at — https://redcircle.com/women-to-watch-r/donationsAdvertising Inquiries: https://redcircle.com/brandsPrivacy & Opt-Out: https://redcircle.com/privacy

Unstable Mass Transfer from a Main-Sequence Star to a Supermassive Black Hole and Quasi-Periodic Eruptions by Itai Linial et al. on Monday 21 November We discuss the formation and evolution of systems comprised of a low-mass ($M_star lesssim 4 , rm M_odot$) main sequence star, orbiting a $10^5-10^7 , rm M_odot$ supermassive black hole with an orbital period of order $sim$hours, and a mild eccentricity ($eapprox0.1-0.2$), episodically shedding mass at each pericenter passage. We argue that the resulting mass transfer is likely unstable, with Roche lobe overflow initially driven by gravitational wave emission, but then being accelerated by the star's expansion in response to its mass loss, undergoing a runaway process. We show that such systems are naturally produced by two-body gravitational encounters within the inner parsec of a galaxy, followed by gravitational wave circularization and inspiral from initially highly eccentric orbits. We argue that such systems can produce recurring flares similar to the recently identified class of X-ray transients known as Quasi-Periodic Eruptions, observed at the centers of a few distant galaxies. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.09851v1

Quasi-periodic eruptions from mildly eccentric unstable mass transfer in galactic nuclei by Wenbin Lu et al. on Monday 17 October We propose that the recently observed quasi-periodic eruptions (QPEs) in galactic nuclei are produced by unstable mass transfer due to Roche lobe overflow of a low-mass (< 0.5Msun) main-sequence star in a mildly eccentric (e ~ 0.5) orbit. We argue that the QPE emission is powered by circularization shocks, but not directly by black hole accretion. Our model predicts the presence of a time-steady accretion disk that is bolometrically brighter than the time-averaged QPE luminosity, but primarily emits in the extreme-UV. This is consistent with the quiescent soft X-ray emission detected in between the eruptions in eROSITA QPE1, QPE2, and GSN 069. Such accretion disks have an unusual $nu L_nu propto nu^{12/7}$ optical spectrum. The lifetime of the bright QPE phase, 100-1000 yrs, is set by mass-loss triggered by ram-pressure interaction between the star and the accretion disk fed by the star itself. We show that the stellar orbits needed to explain QPEs can be efficiently created by the Hills breakup of tight stellar binaries provided that (i) the stellar binary orbit is tidally hardened before the breakup due to diffusive growth of the f-mode amplitude, and (ii) the captured star's orbit decays by gravitational wave emission without significant orbital angular momentum diffusion (which is the case for black holes less than about a million Msun). We conclude by discussing the implications of our model for hyper-velocity stars, extreme mass ratio inspirals, repeating partial TDEs, and related stellar phenomena in galactic nuclei. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2210.08023v1

Ultraviolet Spectropolarimetry:Conservative and Nonconservative Mass Transfer in OB Interacting Binaries by Geraldine J. Peters et al. on Thursday 13 October One objective of the Polstar spectropolarimetry mission is to characterize the degree of nonconservative mass transfer that occurs at various stages of binary evolution, from the initial mass reversal to the late Algol phase. The proposed instrument combines spectroscopic and polarimetric capabilities, where the spectroscopy can resolve Doppler shifts in UV resonance lines with 10 km/s precision, and polarimetry can resolve linear polarization with 1e-3 precision or better. The spectroscopy will identify absorption by mass streams seen in projection against the stellar disk as a function of orbital phase, hot accretion spots, as well as scattering from extended splash structures, circumbinary disks, and other flows in and above/below the orbital plane (e.g. jets) that fail to be transferred conservatively. The polarimetry affects more the light coming from material not seen against the stellar disk, allowing the geometry of the scattering to be tracked, resolving ambiguities left by the spectroscopy and light-curve information. For example, nonconservative mass streams ejected in the polar direction will produce polarization of the opposite sign from conservative transfer accreting in the orbital plane. Also, time domain coverage over a range of phases of the binary orbit are well supported by the Polstar observing strategy. Combining these elements will significantly improve our understanding of the mass transfer process and the amount of mass that can escape from the system, an important channel for changing the final mass, and ultimate supernova, of the large number of massive stars found in binaries at close enough separation to undergo interaction. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2111.14047v4

Quasi-Periodic Erupters: A Stellar Mass-Transfer Model for the Radiation by Julian H. Krolik et al. on Wednesday 07 September Quasi-Periodic Erupters (QPEs) are a remarkable class of objects exhibiting very large amplitude quasi-periodic X-ray flares. Although numerous dynamical models have been proposed to explain them, relatively little attention has been given to using the properties of their radiation to constrain their dynamics. Here we show that the observed luminosity, spectrum, repetition period, duty cycle, and fluctuations in the latter two quantities point toward a model in which: a main sequence star on a moderately eccentric orbit around a supermassive black hole periodically transfers mass to the Roche lobe of the black hole; orbital dynamics lead to mildly-relativistic shocks near the black hole; and thermal X-rays at the observed temperature are emitted by the gas as it flows away from the shock. Strong X-ray irradiation of the star by the flare itself augments the mass transfer, creates fluctuations in flare timing, and stirs turbulence in the stellar atmosphere that amplifies magnetic field to a level at which magnetic stresses can accelerate infall of the transferred mass toward the black hole. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2209.02786v1

The Arizona State Sun Devils football program finally had something go their way with defensive lineman Omarr Norman-Lott withdrawing his name from the transfer portal and opting to return to Tempe for 2022. This news couldn't have come at a better time either, as host Richie Bradshaw talks about a potential blueprint for the Sun Devils football team for 2022. With all the losses the team has endured via the transfer portal, NFL Draft, and graduating players, how on earth can ASU hope to compete in 2022 and not be a door mat for the PAC-12? We talk about all of this on a Wednesday edition of the Locked On Sun Devils podcast! Built Bar is a protein bar that tastes like a candy bar. Go to builtbar.com and use promo code “LOCKED15,” and you'll get 15% off your next order. Amazing selection. Reliably low prices. All the parts your car will ever need. Visit RockAuto.com and tell them Locked On sent you. Learn more about your ad choices. Visit podcastchoices.com/adchoices

In 1995, an 18 year old named Reggie was serving a life sentence inside one of the most violent prisons in the USA. Reggie tried to keep his head down to avoid trouble, but at some point he offended an inmate they called “The Devil”… and when you upset The Devil, you're doomed. But Reggie wasn't going to just roll over and die. Instead, he made a plan to save himself... What happened next shocked the world. For 100s more stories like this one, check out my YouTube channel just called "MrBallen" -- https://www.youtube.com/c/MrBallen If you want to reach out to me, contact me on Instagram, Twitter or any other major social media platform, my username on all of them is @MrBallen SPOILERS BELOW THIS POINT: . . . . Main Sources: 1. Survivors guide to prison – https://www.imdb.com/title/tt4323370/ 2. Calipatria video – https://www.youtube.com/watch?v=YctyQDiJ9wQ 3. Wikipedia – https://en.wikipedia.org/wiki/Calipatria_State_Prison 4. Jails in CA – https://www.allprobailbond.com/blog/california-jails/the-best-and-worst-jails-in-california/ 5. How prison works – https://templeton1.org/california/state/calipatria-state-prison/ 6. Riot – https://www.latimes.com/local/lanow/la-xpm-2014-mar-11-la-me-ln-calipatria-prison-riot-20140311-story.html 7. Rape – https://en.wikipedia.org/wiki/Prison_rape_in_the_United_States 8. 2020 audit – https://www.cdcr.ca.gov/prea/wp-content/uploads/sites/186/2020/08/CAL-2019-PREA-Final-Report.pdf 9. Info Calipatria – https://www.laweekly.com/friends-wrongfully-imprisoned-for-nearly-two-decades-until-the-innocence-project-won-their-freedom/ 10. Mass Transfer – https://www.prisonlegalnews.org/news/1996/sep/15/mass-transfer-madness/ 11. Legal materials – https://www.prisonlegalnews.org/news/1996/mar/15/prison-officials-cant-moot-law-library-suit-by-transfer/#case-1185 12. Electric fence – https://www.prisonlegalnews.org/news/2020/mar/3/lethal-prison-electric-fences-may-violate-international-law/ 13. Prisoner assault – https://www.prisonlegalnews.org/news/1995/sep/15/ca-prisoners-assault-prison-office/ 14. Innocence Project -- https://crimestory.com/2021/10/11/ca-innocence-project-reggie-cole-freed-from-15-year-nightmare-of-unjust-captivity/ 15. Rolling Stone -- https://www.rollingstone.com/politics/politics-news/how-a-wrongfully-convicted-inmate-killed-his-way-out-of-prison-153932/ 16. LA Times - https://www.latimes.com/local/crime/la-me-0412-lapd-suit-20150412-story.html For rest of sources - https://docs.google.com/document/d/1FFEiYxFNEnouGeIUAsYJ16rUlX_Y79yg_J107p5GVxs/edit?usp=sharing

What is the single most measured thing in fire science? The answer is easy - temperature. We use it everywhere - from learning material properties in TGA's to expressing conditions in compartment fires. We use it at the same time to define exposure conditions for our structures and the acceptance criteria within them. We even use it in evacuation studies to define the tenability criteria for occupants... We measure temperature. Everywhere and all the time.But is it really the thing we are looking for? Often temperature measurements become a proxy for heat transfer or energy balance problems, which in many cases are the things that we are looking for. In this episode, I'm going to talk about the wonderful world of heat transfer in fires, temperature measurements and its role in Fire Science and Fire Safety Engineering. In the end, I will give you four pieces of advice on how to improve the understanding of what you are measuring, so hopefully, you will stay with me till the end!--- LinkedIn discussion thread --- https://www.linkedin.com/posts/fire-science-show_011-why-temperature-is-so-easy-to-measure-activity-6826039859526856704-Np2T --- Useful links ---Papers mentioned in the episode:J. Torero, A. Law, C. Maluk - Defining the thermal boundary condition for protective structures in fire: https://linkinghub.elsevier.com/retrieve/pii/S0141029616311841E. Rackauskaite - Improved travelling fires methodology (PhD thesis) https://spiral.imperial.ac.uk/handle/10044/1/52917M. Heidari, P. Kotsovinos, G. Rein - Flame extension and the near field (...) https://onlinelibrary.wiley.com/doi/abs/10.1002/fam.2773M. Beshir et al. - Semi-empirical model for estimating the heat release rate required for flashover (...) thermally-thin boundaries (...) - https://www.sciencedirect.com/science/article/abs/pii/S0379711220300862?via%3DihubIncropera's Fundamentals of Heat and Mass Transfer: https://www.wiley.com/en-us/Fundamentals+of+Heat+and+Mass+Transfer%2C+8th+Edition-p-ES81119320425U. Wickstrom - Temperature Calculation in Fire Safety Engineering https://www.springer.com/gp/book/9783319301709J. Toreros lecture 5 at Princeton https://www.youtube.com/watch?v=HdNGV9jYAU0(the whole course: https://www.youtube.com/playlist?list=PLbInEHTmP9VZjxk0XxzflwUwbCTqzcI_w) 

This week on The Sci-Files, Chelsie and Danny interview Kaitlyn Casulli.Kaitlyn is a third-year Ph.D. student in Biosystems Engineering. Prior to coming to MSU, she received her Bachelor of Science in Food Science at North Carolina State University. Her dissertation focuses on relating heat and mass transfer kinetics to microbial inactivation during dry roasting, using peanuts as a case study. She is currently developing a model to simulate Salmonella inactivation on shelled peanuts in a flat-bed roaster, with a goal of relating the predicted inactivation to salmonellosis risk in roasted products. Eventually, she hopes to continue her research in risk modeling and process validation either as a university professor or as a consultant.Kaitlyn also serves as the treasurer for the Council of Graduate Students (COGS). Before becoming treasurer, she served as her department's COGS representative for two years, during which she was chair of the mental health committee, which organized MSU's first-ever celebration of World Suicide Prevention Day. She has also served on a number of university committees tasked with mental health reform and supporting students with disabilities.If you're interested in talking about your MSU research on the radio or nominating a student, please email Chelsie and Danny at scifiles@impact89fm.org. Check The Sci-Files out on Twitter @SciFiles89FM and on Facebook!

Every year, thousands... Lakhs, actually, of people look forward to IIT Bombay's annual cultural festival in December, Mood Indigo. It's a massive show that sees engineering students (and then some) from all over briefly forgetting Fermat and Mass Transfer and focusing on rock shows, events and informals. As one can imagine, pulling off an event of such scale is a huge process that starts way back in April itself. Simblified speaks to Karan and Chaitanya from the current Mood Indigo organising team to learn how it's done and it's a fascinating chat! NEW TO SIMBLIFIED? It's an Indian podcast - probably the best to come from Malad West - that takes things that happen around us, and deconstructs them in a language you can understand, often surmounting several puns and PG Wodehouse references along the way. We aim to make you appear smarter during parties, job interviews, and dates. Your hosts (and Twitter / Instagram handles) are Chuck (@chuck_gopal / @chuckofalltrades), Srikeit (@srikeit, @srikeit) and Naren (@shenoyn, @shenoynv). We are part of the IVM Podcast network, who, till this day, wonder why they signed us on. For more awesome IVM podcasts,find us at:  Website: Indusvox.com Facebook: facebook.com/ivmpodcasts Twitter: twitter.com/ivmpodcasts Instagram: instagram.com/ivmpodcasts

Every year, thousands... Lakhs, actually, of people look forward to IIT Bombay's annual cultural festival in December, Mood Indigo. It's a massive show that sees engineering students (and then some) from all over briefly forgetting Fermat and Mass Transfer and focusing on rock shows, events and informals. As one can imagine, pulling off an event of such scale is a huge process that starts way back in April itself. Simblified speaks to Karan and Chaitanya from the current Mood Indigo organising team to learn how it's done and it's a fascinating chat! While entry to Mood Indigo is for students, anyone can attend the famed pro nite concert, which this year, will feature British progressive metal giants Haken (much to Chuck's glee). Tickets here: https://insider.in/haken-livewire-nite-at-mood-indigo-dec22-2017/event You can listen to this show and other awesome shows on the IVM Podcast App on Android: https://goo.gl/tGYdU1 or iOS: https://goo.gl/sZSTU5 You can check out our website at http://www.ivmpodcasts.com/

Gudrun unterhält sich diesmal mit Johanna Mödl. Johanna hat von August bis Oktober 2017 ihre Bachelorarbeit Analytische und numerische Untersuchungen zum mikrowelleninduzierten Temperaturanstieg von zylindrischen Probekörpern aus Beton geschrieben. Der Hintergrund war ein Thema aus dem Institut für Massivbau und Baustofftechnologie (Abt. Baustoffe und Betonbau). Dort wird untersucht, wie hochenergetische Mikrowellen solche Temperaturunterschiede in (trockenen) Betonkörpern erzeugen, dass der Werkstoff an der Oberfläche zerstört wird. Um Erfahrungswerte im Umgang mit diesem Verfahren zu erhalten, werden derzeit Laborexperimente durch das Institut für Massivbau und Baustofftechnologie und das Institut für Hochleistungsimpuls- und Mikrowellentechnik, beides Institute des Karlsruher Instituts für Technologie, durchgeführt. Auf Basis der Messergebnisse wird versucht, den Vorgang durch einfache Gleichungen zu beschreiben, um vorhersagen zu können, wie er sich in größerem Maßstab verhält. Aufgrund der Komplexität des Prozesses werden nur vereinfachende Modelle betrachtet. Da diese sich durch partielle Differentialgleichungen beschreiben lassen, sollte der Vorgang während der Bachelorarbeit aus mathematischer Sicht analysiert werden. Die Ausbreitung der Mikrowellen-Energie als Wärme im Baustoff wird durch die Wärmeleitungsgleichung gut beschrieben. Dies ist eine in der Mathematik wohlstudierte Gleichung. Im Allgemeinen lassen sich aber analytische Lösungen nur schwer oder gar nicht berechnen. Daher mussten zusätzlich numerische Verfahren gewählt und implementiert werden, um eine Approximation der Lösung zu erhalten. Johanna entschied sich für das Finite-Differenzen-Verfahren im Raum und ein explizites Eulerverfahren in der Zeitrichtung, da beide einfach zu analysieren und zu implementieren sind. Erfreulicherweise stimmt die numerisch auf diese Weise approximierte Lösung mit den experimentellen Ergebnissen in den hauptsächlichen Gesichtspunkten überein. Die Wärme breitet sich von der Quelle in den Beton aus und es kommt im zeitlichen Verlauf zu einer kontinuierlichen Erwärmung in den Körper hinein. Das größte Problem und die vermutliche Ursache dafür, dass die Meßdaten noch nicht ganz genau mit den Simulationen übereinstimmen ist, dass man physikalisch sinnvollere Randbedingungen bräuchte. Im Moment wird - wie üblich - davon ausgegangen, dass am Rand des Betonzylinders, wo nicht die Energie eintritt, der Körper Umgebungstemperatur hat. Hier bräuchte man eine phyiskalische Modellierung, die das korrigiert. Literatur und weiterführende Informationen W. Hackbusch: Theorie und Numerik elliptischer Differentialgleichungen, Springer Spektrum, Wiesbaden, 4. Auflage, 2017. B. Lepers e.a.: A drying and thermoelastic model for fast microwave heating of concrete. Global Digital Central, Frontiers in Heat and Mass Transfer, 2014. M. Umminger e.a.: Ablation kontaminierter Oberflächen zementgebundener Bauteile beim Rückbau kerntechnischer Anlagen. Abschlussbericht, BMBF- Förderkennzeichen 02S8709 und 02S8719, Februar 2015.

Thomas Henn hat im Oktober 2016 seine Promotion zum Thema Computersimulation von Partikelströmungen abgeschlossen. Partikelströmungen treten in zahlreichen natürlichen sowie künstlichen Vorgängen auf, beispielsweise als Transport von Feinstaub in den menschlichen Atemwegen, als Bildung von Sediment in Flüssen oder als Feststoff–Fluid Gemisch bei Filtrationen. Simulationen von Partikelströmungen kommen zum Einsatz, wenn physische Untersuchungen nicht möglich sind. Darüber hinaus können sie Kosten experimenteller Studien verringern. Häufig ist das der Fall, wenn es um medizinische Anwendungen geht. Wenn man beispielsweise aus CT-Aufnahmen die genaue Geometrie des Naseninnenraums eines Patienten kennt, kann durch Simulation in dieser spezifischen Geometrie ermittelt werden, wo sich Partikel welcher Größe ablagern. Das ist in zwei Richtungen interessant: Erstens zur Vermeidung von Gesundheitsbelastungen durch Einlagerung von Partikeln in der Lunge (dort landen alle Partikel, die die Nase nicht filtern kann) aber zweitens auch bei der bestmöglichen Verabreichung von Medikamenten mittels Zerstäubung in die Nasenhöhle. Es hat sich gezeigt, dass die Simulation von Strömungen mit einer großen Zahl an beliebig geformten Partikeln den herkömmlichen numerischen Methoden insbesondere bei der Parallelisierung Probleme bereitet. Deshalb wird die Lattice Boltzmann Methode (LBM) als neues Verfahren zur numerischen Simulation von Strömungen auf Partikelströmungen angewendet. Sie hat außerdem den Vorteil, dass komplexe Geometrien wie z.B. ein Naseninnenraum keine extra zu bewältigende Schwierigkeit darstellen. Die zentrale Idee für die effektive Parallelisierung unter LBM ist eine Gebietszerlegung: Die durchströmte Geometrie wird in Zellen aufgeteilt und diese Zellen gerecht auf die zur Verfügung stehenden Prozessoren verteilt. Da die Rechnungen für die Strömungsrechnung mit LBM im wesentlichen lokal sind (es werden nur die Informationen einer Zelle und der direkten Nachbarzellen benötigt), ist das extrem effektiv. Wenn nun neben der Strömung auch noch die Bewegung der Partikel berechnet werden soll, müssen natürlich physikalische Bewegungsmodelle gefunden werden, die für die jeweilige Partikelgröße und -form passen, daraus Gleichungen und deren Diskretisierung abgeleitet werden in der Implementierung die Vorteile der LBM bei der Parallelisierung möglichst nicht zerstört werden. Offensichtlich ist es am besten, wenn die Partikel möglichst gleichmäßig über die durchströmte Geometrie verteilt sind. Aber das kann man sich ja nicht immer so aussuchen. Je nach Größe und Dichte der Partikel wird es wichtig, neben der Wirkung des Fluids auf die Partikel auch Rückwirkung des Partikels auf die Strömung, Wechselwirkung der Partikel untereinander (z.B. auch herausfinden, wann sich Partikel berühren) Wechselwirkung der Partikel mit dem Rand der Geometriezu betrachten. Als sehr hilfreich hat sich eine ganz neue Idee herausgestellt: Partikelströmungen als bewegtes poröses Medium zu modellieren. D.h. für große Partikel stellt man sich vor, sie haben einen festen Kern und außen einen glatten Übergang in der Porösität zur reinen Fluidphase. Es zeigt sich, dass man dann sogar auf ein Modell verzichten kann, das die Kontakte der Partikel modelliert, weil sich die Partikel so natürlich in der Strömung bewegen, wie man es auch im Experiment beobachtet. Alle Berechnungen müssen validiert werden, auch wenn manchmal nicht ganz klar ist, wie das erfolgen kann. Zum Glück ist hier aber die enge Zusammenarbeit mit der Verfahrenstechnik am KIT eine große Hilfe, die die Computersimulationswerkzeuge auch für ihre Projekte nutzen und weiter entwickeln. Literatur und weiterführende Informationen L.L.X. Augusto: Filters, Gespräch mit G. Thäter im Modellansatz Podcast, Folge 112, Fakultät für Mathematik, Karlsruher Institut für Technologie (KIT), 2016. http://modellansatz.de/filters OpenLB Open source Lattice Boltzmann Code F. Bülow: Numerical simulation of destabilizing heterogeneous suspensions at vanishing Reynolds numbers. Karlsruhe, 2015. T. Henn et al.: Particle Flow Simulations with Homogenised Lattice Boltzmann Methods. To appear in Particuology. F. Klemens: Simulation of Fluid-Particle Dynamics with a Porous Media Lattice Boltzmann Method, MA thesis. Karlsruher Institut für Technologie, 2016. E. E. Michaelides: Particles, Bubbles & Drops: Their Motion, Heat and Mass Transfer, World Scientific Publishing Company Incorporated, 2006. T.Henn: Aorta Challenge, Gespräch mit S. Ritterbusch im Modellansatz Podcast, Folge 2, Fakultät für Mathematik, Karlsruher Institut für Technologie (KIT), 2013. http://modellansatz.de/aorta-challenge

Oliver, J (University of Oxford) Monday 23 June 2014, 16:00-16:30

Oliver, J (University of Oxford) Monday 23 June 2014, 16:00-16:30

Four animations showing adsorption and solute transport in a very easy to understand format.

Four animations showing adsorption and solute transport in a very easy to understand format.

Transcript: How does mass transfer occur in a close binary pair? The Roche surface or lobes define the region of space where gas is bound to one or both stars. If either star becomes a giant the outer layers swell to fill the lobe, and the teardrop shape becomes the actual surface of the star. In the first stage of binary evolution neither star fills its Roche lobes. In the second stage the more massive star becomes a giant first and fills its Roche lobe. Mass then flows at the point between the lobes like sand through an hourglass onto the lower mass star causing it to gain mass. In the third stage the lower mass star becomes a giant and fills its Roche lobe producing a contact binary. In the process of mass transfer the fundamental course of stellar evolution for each star in a binary is altered with interesting consequences.