Artificial stomach reveals fluid dynamics of food digestion
Droplet breakup shows how lower stomach contraction waves classify foods


Date:
August 3, 2021
Source:
American Institute of Physics
Summary:
Scientists have extensively studied how gastric juices in the
stomach break down ingested food and other substances. However,
less is known about how complex flow patterns and mechanical
stresses in the stomach contribute to digestion. Researchers
built a prototype of an artificial antrum to present a deeper
understanding of how physical forces influence food digestion
based on fluid dynamics. They reveal a classifying effect based
on the breakup of liquid drops combined with transport phenomena.



FULL STORY ==========================================================================
In efforts to fight obesity and enhance drug absorption, scientists have extensively studied how gastric juices in the stomach break down ingested
food and other substances. However, less is known about how the complex
flow patterns and mechanical stresses produced in the stomach contribute
to digestion.


========================================================================== Researchers from France, Michigan, and Switzerland built a prototype of an artificial antrum, or lower stomach, to present a deeper understanding of
how physical forces influence food digestion based on fluid dynamics. In Physics of Fluids, by AIP Publishing, they reveal a classifying effect
based on the breakup of liquid drops combined with transport phenomena
derived from complementary computer simulations.

The relevant parts of the stomach are the corpus, where food is stored;
the antrum, where food is ground; and the pylorus, or pyloric sphincter,
the tissue valve that connects to the small intestine. Slow-wave muscle contractions begin in the corpus, with wave speed and amplitude increasing
to form the antral contraction waves (ACWs) as they propagate toward
the pylorus.

The researchers' antrum device consists of a cylinder, capped at one
end to imitate a closed pylorus, and a hollow piston that moves inside
the cylinder to replicate ACWs. As verified through computer simulations
and experimental measurements, the protype produces the characteristics
of retropulsive jet flow that exist in the antrum.

Food disintegration is quantified by determining the breakup of liquid
drops in flow fields produced by ACWs. The researchers studied different
model fluid systems with various viscosity to account for the broad
physical properties of digested food. The drop size and other parameters resemble conditions in a real stomach.

Drop breakup occurred near the surface of the hollow piston, where
the flow field exhibited slower velocities but higher strain rates,
thus exposing the drop to higher shear stresses during a longer period
of time. No breakup occurred for drops near the center of the piston,
because the stresses and residence times are smaller and shorter.

"The results extracted from this simple prototype have deepened insights
into the disintegration process that takes place in the stomach,"
co-author Damien Dufour said. "Drops near the wall will break up as they
are transported toward the pylorus. The drops in the center return toward
the corpus, without major size reduction, to disintegrate later. One
may perceive this combined action of the ACWs as a classifying effect." ========================================================================== Story Source: Materials provided by American_Institute_of_Physics. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. D. Dufour, F. X. Tanner, K. A. Feigl, E. J. Windhab. Investigation
of the
dispersing characteristics of antral contraction wave flow in a
simplified model of the distal stomach. Physics of Fluids, 2021;
33 (8): 083101 DOI: 10.1063/5.0053996 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210803121312.htm

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