Talk:Hemodynamics

message: I have proposed that Haemodynamic response be merged into this article. Haemodynamic response seems to cover one aspect of haemodynamics, specific to the brain. I don't think it contains enough information to warrant a separate article. However, if there is a completely different medical context in which the term "haemodynamic response" is used, please explain below. Otherwise, if there are no other serious objections, then I'll effect the merger within a week. Cheers. – Liveste (talk • edits) 00:08, 27 March 2008 (UTC)
replies: text: I disagree.  The Haemodynamic response (function) is an important concept in functional brain imaging and, I believe, important enough and distinct enough in that context to warrant an independent article.  Perhaps to emphasize this point the other article should be actually be renamed "Haemodynamic response function" and re-written to better describe the role of the Haemodynamic response in neruoimaging.  I do agree that the article there is not particularly detailed, but that is not a good reason to merge them.  I think a pointer from this article to that one would be better.  My main reason for this belief, is that this article is primarily about the heart and circulation whereas the other article should be primarily about how a particular aspect of haemodynamics related to imaging. 128.200.46.67 (talk) 23:39, 3 June 2008 (UTC)
replies: text: Sorry for the long delay. Thank you for explaining the difference between the two articles and how each are distinctly useful. I'll remove the merge tags and keep the articles the way they are. Cheers. – Liveste (talk • edits) 22:26, 19 September 2008 (UTC)

text: Titles do need changing so at least the spelling is consistent. I think they also need changing to explain they concentrate on different aspects of the subjects, if that is what they do. I suspect though that this distinction intended by some editors is not as clear in the articles themselves. Sandpiper (talk) 08:49, 30 November 2015 (UTC)
thread_title:  Merge proposal 

message: I propose a merge the article blood flow into Hemodynamics, since blood flow is a central part of hemodynamics. --Rudolf Hellmuth (talk) 13:22, 5 December 2013 (UTC)
replies: text: Support: I support the merge. DiptanshuTalk 14:11, 9 December 2013 (UTC)

text: Support:  Yes, merging is perfectly appropriate.  Rather than do it in one session you can shift topics, one at a time, until all the information is here.  Then delete blood flow article.  ... PeterEasthope (talk) 15:11, 11 October 2015 (UTC)

text: Cautious Support: On the face of it I see no difference in the meaning of the two titles, so they should not be separate articles. I am cautious because this is potentially a highly specialist subject, so there might be important shades of meanings. One the other hand, having two articles with titles having virtually the same meanings in common English simply confuses a non expert reader such as myself. Either merge or make clear why there needs to be two separate articles dealing with different aspects, with distinguishable titles.Sandpiper (talk) 08:06, 30 November 2015 (UTC)
thread_title:  Merge from blood flow 

message: Without accusing one author or the other, but this article seems to copy quite extensively (and verbatim) from this page on blood flow (and other aspects). Does this merit a complete rewrite? Mfhulskemper (talk) 13:54, 3 March 2014 (UTC)
replies: text: Almost certainly. 67.245.219.168 (talk) 22:04, 8 July 2018 (UTC)
thread_title:  Copy/Paste action? : ) 

message: There is quite a hefty chunk of hemodynamics on the Blood pressure page that could be split off into a separate article.  It would be a good fit for expanding this article.  Gccwang (talk) 05:05, 23 August 2014 (UTC)
thread_title:  Merge from Blood_pressure#Hemodynamics 

message: I believe that the merger should not be done, it makes it harder for students to research on the specific things. despite hemodynamics and blood vessels being similar, there are some specific information that students/anyone else may be looking for under the specific 2 topics. If we merger them, one may find it confusing to find the specific point which they need for a project or research. 
110.92.124.252 (talk) 00:51, 13 October 2015 (UTC)
thread_title:  Disadvantages of merger 

message: Fluids dynamics are made for fluids with atomic and molecular continuous bonds. Blood is a discontinuous and heterogeneous tissue of formed elements and liquids which never stay at the same place and wherein the formed elements break the fluids bonds.
Fluids are always the same everywhere. Blood distribution or blood components organization is very different in channels, rotative cells, filter, sedimentation, smurs, drops, leaks. The apparent viscosity is a result from red cells separation.
So there is not a big fluids dynamics in blood.
So blood flow depends depends on the types flows.  — Preceding unsigned comment added by 193.57.120.117 (talk) 07:15, 22 November 2016 (UTC)
thread_title:  hemodynamics / blood flow  

message: Blood flows in a vessel or in a channel according to two separated flows : a sheath flow and a plug flow.
So fluid dynamics is not for blood.
A fluid is continuously linked by the same atomic or molecular bonds everywhere (droplet, channel flow, smear, close to a wall, fully developed flow).
Blood substence is quite different : cells, red cells, white cells, platelets, serum, macrmolécules, fibres, proteins, viruses, etc... etc... will break and move under drag, lift ad inertial forces in different places. Blood sedimentates but a fluid does not sedimentate. Blood components separate and aggregate but a fluid does not see its atoms or molecules separate.
Fluids can be approached by finite deifferences where a point can represent a volume of conservative properties. But blood cannot be segmented in the same way because we cannot cut cells. And in different flow locations cells are not having the same distribution.
Viscosity in fluid is a coefficient between shear stress and shear rate obtained between parallel fluid layers of different velocities. This originates the parabolic velocity profile in Poiseuille's flow.
Viscosity in blood relatively apparently relates to a sheared flow but it is exactly not a shear rate as in a fluid.
So blood dynamics, alias hemodynamics, is the description of the movements : blood substence, blood velocities, blood forces. And blood flow is the description of blood in the streams : migrations, separations, etc...
Two received ideas on blood flow are exaggerated :
1-Poiseuille flow. Poiseuille measured blood pressure but the Poiseuille flow is for water, and is never found in blood, which never flows according to a parabolic velocity profile as it was due in Poiseuille's law and a Poiseuille flow.
2- Blood viscosity is not definable. As many flowing materials are defined by their viscosity, we have to admit that blood flow is not a fluid flow neither a complex fluid flow as expected in shear rate and shear stress theory to calculate tangential friction force between parallel layers by intermediary of viscosity. Viscosity characterizes the friction between atoms and molecules in a fluid holding continuous atomic bonds which make a fluid stand as a fluid in bulk and developed flows or in a droplet or attach to the wall boundaries. Blood matter is constantly traversed by RBCs, Proteins, Platelets, fibres, aggregates or clots. These solid components constitute more than 50% of complete blood. They break the continuity of plasma and do not allow viscous fluid layers purchase their continuous friction force that slows down the streamlines. Moreover, these components are lifted and migrate in the high energy streams and make the slowest flows poor in solid components.
There are many different blood flows :
1 Sedimentation
2 Centrifugation
3 Shaking
4 Couette flow
5 Rotating plane-plane flow
6 Cone-plane flow
7 Straight channel
8 Smear
9 Filtration
All these flows change the blood state of matter.  — Preceding unsigned comment added by Alxdetilly (talk • contribs) 10:41, 24 November 2016 (UTC)
thread_title:  the real difference between hemodynamics and blood flow 

message: Blood flow is an incompressible fluid having density nearly equal to that of water.A high concentration of red blood cells increases its viscosity from three to five times that of water. 103.153.117.253 (talk) 11:28, 25 November 2021 (UTC)
thread_title:  Blood flow