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Modeling the fluid dynamics in a human stomach to gain insight of food digestion.

Ferrua MJ, Singh RP - J. Food Sci. (2010)

Bottom Line: During gastric digestion, food is disintegrated by a complex interaction of chemical and mechanical effects.By increasing the viscosity, the formation of the 2 flow patterns commonly regarded as the main mechanisms driving digestion (i.e., the retropulsive jet-like motion and eddy structures) was significantly diminished, while a significant increase of the pressure field was predicted.These results were in good agreement with experimental data previously reported in the literature, and suggest that, contrary to the traditional idea of a rapid and complete homogenization of the meal, gastric contents associated with high viscous meals are poorly mixed.

View Article: PubMed Central - PubMed

Affiliation: Riddet Inst., Massey Univ., Palmerston North, New Zealand.

ABSTRACT

Unlabelled: During gastric digestion, food is disintegrated by a complex interaction of chemical and mechanical effects. Although the mechanisms of chemical digestion are usually characterized by using in vitro analysis, the difficulty in reproducing the stomach geometry and motility has prevented a good understanding of the local fluid dynamics of gastric contents. The goal of this study was to use computational fluid dynamics (CFD) to develop a 3-D model of the shape and motility pattern of the stomach wall during digestion, and use it to characterize the fluid dynamics of gastric contents of different viscosities. A geometrical model of an averaged-sized human stomach was created, and its motility was characterized by a series of antral-contraction waves of up to 80% relative occlusion. The flow field within the model (predicted using the software Fluentâ„¢) strongly depended on the viscosity of gastric contents. By increasing the viscosity, the formation of the 2 flow patterns commonly regarded as the main mechanisms driving digestion (i.e., the retropulsive jet-like motion and eddy structures) was significantly diminished, while a significant increase of the pressure field was predicted. These results were in good agreement with experimental data previously reported in the literature, and suggest that, contrary to the traditional idea of a rapid and complete homogenization of the meal, gastric contents associated with high viscous meals are poorly mixed. This study illustrates the capability of CFD to provide a unique insight into the fluid dynamics of the gastric contents, and points out its potential to develop a fundamental understanding and modeling of the mechanisms involved in the digestion process.

Practical application: This study illustrates the capability of computational fluid dynamic techniques to provide a unique insight into the dynamics of the gastric contents, pointing out its potential to develop a fundamental understanding and modeling of the human digestion process.

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Related in: MedlinePlus

Effect of viscosity on the formation of the retropulsive-jet like motion and eddy structures. Streamlines of the fluid flow within the stomach's middle plane at t+ 10 s, colored by velocity magnitude (cm/s).
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fig08: Effect of viscosity on the formation of the retropulsive-jet like motion and eddy structures. Streamlines of the fluid flow within the stomach's middle plane at t+ 10 s, colored by velocity magnitude (cm/s).

Mentions: As a result of the motor activity of the gastric wall, a highly 3-D flow was predicted within the stomach, independently of the viscosity of the fluid. The strongest fluid motions were also always predicted in the lower part of the stomach, while a slow recirculation of gastric contents from the proximal to the distal stomach was also identified. These results (illustrated in Figure 7 in the case of the 0.001 Pa.s fluid) are in good agreement with the classical description of gastric functions, where the upper part of the stomach acts as a reservoir and supplier of gastric contents to the antrum, whereas the lower part is responsible for the mechanical forces and fluid motions that promotes their breakdown and mixing (Pal and others 2007; Kong and Singh 2008a). However, unlike these overall flow patterns, the local characteristics of the flow field within the stomach were significantly influenced by the viscosity of the fluid (Figure 8).


Modeling the fluid dynamics in a human stomach to gain insight of food digestion.

Ferrua MJ, Singh RP - J. Food Sci. (2010)

Effect of viscosity on the formation of the retropulsive-jet like motion and eddy structures. Streamlines of the fluid flow within the stomach's middle plane at t+ 10 s, colored by velocity magnitude (cm/s).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2992692&req=5

fig08: Effect of viscosity on the formation of the retropulsive-jet like motion and eddy structures. Streamlines of the fluid flow within the stomach's middle plane at t+ 10 s, colored by velocity magnitude (cm/s).
Mentions: As a result of the motor activity of the gastric wall, a highly 3-D flow was predicted within the stomach, independently of the viscosity of the fluid. The strongest fluid motions were also always predicted in the lower part of the stomach, while a slow recirculation of gastric contents from the proximal to the distal stomach was also identified. These results (illustrated in Figure 7 in the case of the 0.001 Pa.s fluid) are in good agreement with the classical description of gastric functions, where the upper part of the stomach acts as a reservoir and supplier of gastric contents to the antrum, whereas the lower part is responsible for the mechanical forces and fluid motions that promotes their breakdown and mixing (Pal and others 2007; Kong and Singh 2008a). However, unlike these overall flow patterns, the local characteristics of the flow field within the stomach were significantly influenced by the viscosity of the fluid (Figure 8).

Bottom Line: During gastric digestion, food is disintegrated by a complex interaction of chemical and mechanical effects.By increasing the viscosity, the formation of the 2 flow patterns commonly regarded as the main mechanisms driving digestion (i.e., the retropulsive jet-like motion and eddy structures) was significantly diminished, while a significant increase of the pressure field was predicted.These results were in good agreement with experimental data previously reported in the literature, and suggest that, contrary to the traditional idea of a rapid and complete homogenization of the meal, gastric contents associated with high viscous meals are poorly mixed.

View Article: PubMed Central - PubMed

Affiliation: Riddet Inst., Massey Univ., Palmerston North, New Zealand.

ABSTRACT

Unlabelled: During gastric digestion, food is disintegrated by a complex interaction of chemical and mechanical effects. Although the mechanisms of chemical digestion are usually characterized by using in vitro analysis, the difficulty in reproducing the stomach geometry and motility has prevented a good understanding of the local fluid dynamics of gastric contents. The goal of this study was to use computational fluid dynamics (CFD) to develop a 3-D model of the shape and motility pattern of the stomach wall during digestion, and use it to characterize the fluid dynamics of gastric contents of different viscosities. A geometrical model of an averaged-sized human stomach was created, and its motility was characterized by a series of antral-contraction waves of up to 80% relative occlusion. The flow field within the model (predicted using the software Fluentâ„¢) strongly depended on the viscosity of gastric contents. By increasing the viscosity, the formation of the 2 flow patterns commonly regarded as the main mechanisms driving digestion (i.e., the retropulsive jet-like motion and eddy structures) was significantly diminished, while a significant increase of the pressure field was predicted. These results were in good agreement with experimental data previously reported in the literature, and suggest that, contrary to the traditional idea of a rapid and complete homogenization of the meal, gastric contents associated with high viscous meals are poorly mixed. This study illustrates the capability of CFD to provide a unique insight into the fluid dynamics of the gastric contents, and points out its potential to develop a fundamental understanding and modeling of the mechanisms involved in the digestion process.

Practical application: This study illustrates the capability of computational fluid dynamic techniques to provide a unique insight into the dynamics of the gastric contents, pointing out its potential to develop a fundamental understanding and modeling of the human digestion process.

Show MeSH
Related in: MedlinePlus