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Fluid Dynamics Appearing during Simulated Microgravity Using Random Positioning Machines

Random Positioning Machines (RPMs) are widely used as tools to simulate microgravity on ground. They consist of two gimbal mounted frames, which constantly rotate biological samples around two perpendicular axes and thus distribute the Earth’s gravity vector in all directions over time. In recent ye...

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Detalles Bibliográficos
Autores principales: Wuest, Simon L., Stern, Philip, Casartelli, Ernesto, Egli, Marcel
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5279744/
https://www.ncbi.nlm.nih.gov/pubmed/28135286
http://dx.doi.org/10.1371/journal.pone.0170826
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author Wuest, Simon L.
Stern, Philip
Casartelli, Ernesto
Egli, Marcel
author_facet Wuest, Simon L.
Stern, Philip
Casartelli, Ernesto
Egli, Marcel
author_sort Wuest, Simon L.
collection PubMed
description Random Positioning Machines (RPMs) are widely used as tools to simulate microgravity on ground. They consist of two gimbal mounted frames, which constantly rotate biological samples around two perpendicular axes and thus distribute the Earth’s gravity vector in all directions over time. In recent years, the RPM is increasingly becoming appreciated as a laboratory instrument also in non-space-related research. For instance, it can be applied for the formation of scaffold-free spheroid cell clusters. The kinematic rotation of the RPM, however, does not only distribute the gravity vector in such a way that it averages to zero, but it also introduces local forces to the cell culture. These forces can be described by rigid body analysis. Although RPMs are commonly used in laboratories, the fluid motion in the cell culture flasks on the RPM and the possible effects of such on cells have not been examined until today; thus, such aspects have been widely neglected. In this study, we used a numerical approach to describe the fluid dynamic characteristic occurring inside a cell culture flask turning on an operating RPM. The simulations showed that the fluid motion within the cell culture flask never reached a steady state or neared a steady state condition. The fluid velocity depends on the rotational velocity of the RPM and is in the order of a few centimeters per second. The highest shear stresses are found along the flask walls; depending of the rotational velocity, they can reach up to a few 100 mPa. The shear stresses in the “bulk volume,” however, are always smaller, and their magnitude is in the order of 10 mPa. In conclusion, RPMs are highly appreciated as reliable tools in microgravity research. They have even started to become useful instruments in new research fields of mechanobiology. Depending on the experiment, the fluid dynamic on the RPM cannot be neglected and needs to be taken into consideration. The results presented in this study elucidate the fluid motion and provide insight into the convection and shear stresses that occur inside a cell culture flask during RPM experiments.
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spelling pubmed-52797442017-02-17 Fluid Dynamics Appearing during Simulated Microgravity Using Random Positioning Machines Wuest, Simon L. Stern, Philip Casartelli, Ernesto Egli, Marcel PLoS One Research Article Random Positioning Machines (RPMs) are widely used as tools to simulate microgravity on ground. They consist of two gimbal mounted frames, which constantly rotate biological samples around two perpendicular axes and thus distribute the Earth’s gravity vector in all directions over time. In recent years, the RPM is increasingly becoming appreciated as a laboratory instrument also in non-space-related research. For instance, it can be applied for the formation of scaffold-free spheroid cell clusters. The kinematic rotation of the RPM, however, does not only distribute the gravity vector in such a way that it averages to zero, but it also introduces local forces to the cell culture. These forces can be described by rigid body analysis. Although RPMs are commonly used in laboratories, the fluid motion in the cell culture flasks on the RPM and the possible effects of such on cells have not been examined until today; thus, such aspects have been widely neglected. In this study, we used a numerical approach to describe the fluid dynamic characteristic occurring inside a cell culture flask turning on an operating RPM. The simulations showed that the fluid motion within the cell culture flask never reached a steady state or neared a steady state condition. The fluid velocity depends on the rotational velocity of the RPM and is in the order of a few centimeters per second. The highest shear stresses are found along the flask walls; depending of the rotational velocity, they can reach up to a few 100 mPa. The shear stresses in the “bulk volume,” however, are always smaller, and their magnitude is in the order of 10 mPa. In conclusion, RPMs are highly appreciated as reliable tools in microgravity research. They have even started to become useful instruments in new research fields of mechanobiology. Depending on the experiment, the fluid dynamic on the RPM cannot be neglected and needs to be taken into consideration. The results presented in this study elucidate the fluid motion and provide insight into the convection and shear stresses that occur inside a cell culture flask during RPM experiments. Public Library of Science 2017-01-30 /pmc/articles/PMC5279744/ /pubmed/28135286 http://dx.doi.org/10.1371/journal.pone.0170826 Text en © 2017 Wuest et al http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
Wuest, Simon L.
Stern, Philip
Casartelli, Ernesto
Egli, Marcel
Fluid Dynamics Appearing during Simulated Microgravity Using Random Positioning Machines
title Fluid Dynamics Appearing during Simulated Microgravity Using Random Positioning Machines
title_full Fluid Dynamics Appearing during Simulated Microgravity Using Random Positioning Machines
title_fullStr Fluid Dynamics Appearing during Simulated Microgravity Using Random Positioning Machines
title_full_unstemmed Fluid Dynamics Appearing during Simulated Microgravity Using Random Positioning Machines
title_short Fluid Dynamics Appearing during Simulated Microgravity Using Random Positioning Machines
title_sort fluid dynamics appearing during simulated microgravity using random positioning machines
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5279744/
https://www.ncbi.nlm.nih.gov/pubmed/28135286
http://dx.doi.org/10.1371/journal.pone.0170826
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