PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 12495991

Quantitative flow visualization: toward a comprehensive flow diagnostic tool.

Mory Gharib·Francisco Pereira·Dana Dabiri·Darius Modarress
View original source ↗Export metadata ↓

Abstract

Quantitative flow visualization has many roots and has taken several approaches. The advent of digital image processing has made it practical to extract useful information from every kind of flow image. In a direct approach, the image intensity or color (wavelength or frequency) can be used as an indication of concentration, density and temperature field, or gradients of these scalar fields in the flow.(1) For whole-field velocity measurement, the method of choice for experimental fluid mechanicians has been digital particle image velocimetry (DPIV). This paper presents a novel approach to extend the DPIV technique from a planar method to a full three-dimensional volume mapping technique.

Explore related subjects

Biological TransportKineticsMathematicsModels, BiologicalJournal ArticleResearch Support, U.S. Gov't, Non-P.H.S.

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Mory Gharib, Francisco Pereira, Dana Dabiri, Darius Modarress. 2002. Quantitative flow visualization: toward a comprehensive flow diagnostic tool.. https://doi.org/10.1111/j.1749-6632.2002.tb04546.x

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2003

A study of oxygen transfer in shake flasks using a non-invasive oxygen sensor.

We describe a study of oxygen transfer in shake flasks using a non-invasive optical sensor. This study investigates the effect of different plugs, presence of baffles, and the type of media on the dissolved oxygen profiles during Escherichia coli fermentation. We measured the volumetric mass transfer coefficient (k(L)a) under various conditions and also the resistances of the various plugs. Finally, we compared shake flask k(L)a with that from a stirred tank fermentor. By matching k(L)a's we were able to obtain similar growth and recombinant protein product formation kinetics in both a fermentor and a shake flask. These results provide a quantitative comparison of fermentations in a shake flask vs. a bench-scale fermentor and should be valuable in guiding scale-up efforts.

Biological Transport↗
PubMed2003

Stationary diffusion gradients associated with photosynthetic carbon flux-a study of compartmental versus diffusion-reaction models.

Metabolic processes usually involve diffusion of compounds in addition to their metabolic reactions. Such processes are adequately described by reaction-diffusion models (in the form partial differential equations) which are usually difficult and tedious to solve. Compartmental models (ordinary differential equations) are much easier to analyse but may be inadequate since they do not allow for spatial gradients. However, a compartmental model can be considered as the limit of a reaction-diffusion model for very fast diffusion (all diffusion coefficients D(j)--> infinity ). A compartmental model m(c) is termed "associated" to the reaction-diffusion model m(rd) if m(c) is the limit of m(rd) for all D(j)--> infinity. From the analytical solutions of a reaction-diffusion model and its associated compartmental model the extent of a diffusion gradient of m(rd) can be estimated by means of parameters from both m(c) and m(rd). This approach is extended to more complicated models that cannot be solved analytically. Gradients can be neglected and, consequently, the compartmental description be used, if the characteristic length s of the diffusion path is small compared with the distance a particle travels in time T(e), where T(e) is the characteristic time for the compartmental model. This ratio of lengths can also be expressed as the ratio of two times, namely the residence time s(2)/D(X) and the turnover time X(C)/v, where X(C) and v are the steady-state concentration of X and its import rate, respectively, for the associated compartmental model. Characteristic times are given for several simple reaction-diffusion systems in rectangular and spherical geometries. Intracellular gradients of HCO(3)(-) and CO(2) are calculated for some flux situations relevant to photosynthetic carbon fixation in green microalgae.

Biological Transport↗
PubMed2003

Xylylated dimers of putrescine and polyamines: influence of the polyamine backbone on spermidine transport inhibition.

Dimeric norspermidine and spermidine derivatives are strong competitive inhibitors of polyamine transport. A xylyl tether was used for the dimerization of various triamines and spermine via a secondary amino group, and of putrescine via an ether or an amino group. Dimerization of putrescine moieties potentiates their ability to compete against spermidine transport to a much greater extent than for triamine dimers.

Biological Transport↗