Does inviscid mean shear stress is negligible?

AI Thread Summary
Inviscid flow refers to a fluid with negligible viscosity, implying minimal shear stresses. However, a Reynolds number of 10^5 does not automatically justify ignoring shear stress, especially when calculating drag on an object like a sphere in water. The drag equation includes both pressure and shear stress components, and without specific shear stress data, assuming it is negligible may lead to inaccuracies. While inviscid flow can simplify calculations, it is essential to consider the specific conditions and fluid properties involved. Accurate assumptions are crucial for reliable results in fluid dynamics.
corona7w
Messages
11
Reaction score
0
I have this flow with Reynold's number in the 10^5, which I think it's big enough to treat the fluid as inviscid, does this also mean I can assume the shear stress is negligible?
 
Engineering news on Phys.org
First, what does inviscid mean, by definition?

Second, just because the flow is 10^5 does not mean you can ignore shear stress. What is the object under consideration?
 
It's a sphere with radius R immersed in water of velocity V. I'm asked to calculate the drag on it. I know the formula for drag is integral of Pcos theta dA + integral of shear stress sin theta dA . And I am not given any information regarding the shear stress, so I thought since the Re is pretty big, we might just treat the shear stress as negligible so only the first term of the equation needs to be calculated.
 
You could assume inviscid flow but its probably not an accurate assumption. Whats the viscosity or what fluid are you using?
 
Last edited:
corona7w said:
I have this flow with Reynold's number in the 10^5, which I think it's big enough to treat the fluid as inviscid, does this also mean I can assume the shear stress is negligible?

If u are talking about term "Inviscid"...then u are correct.. its means flow is non viscous ,,,that in return means SHEAR STRESSES are minimum and can be neglected
 

Thread 'Race car suspension Class'

Posted June 2024 - 15 years after starting this class. I have learned a whole lot. To get to the short course on making your stock car, late model, hobby stock E-mod handle, look at the index below. Read all posts on Roll Center, Jacking effect and Why does car drive straight to the wall when I gas it? Also read You really have two race cars. This will cover 90% of problems you have. Simply put, the car pushes going in and is loose coming out. You do not have enuff downforce on the right...
View full post »
Thread 'Physics of Stretch: What pressure does a band apply on a cylinder?'

Thread 'Physics of Stretch: What pressure does a band apply on a cylinder?'

Scenario 1 (figure 1) A continuous loop of elastic material is stretched around two metal bars. The top bar is attached to a load cell that reads force. The lower bar can be moved downwards to stretch the elastic material. The lower bar is moved downwards until the two bars are 1190mm apart, stretching the elastic material. The bars are 5mm thick, so the total internal loop length is 1200mm (1190mm + 5mm + 5mm). At this level of stretch, the load cell reads 45N tensile force. Key numbers...
View full post »

Thread 'Cantilever help'

I'm trying to decide what size and type of galvanized steel I need for 2 cantilever extensions. The cantilever is 5 ft. The space between the two cantilever arms is a 17 ft Gap the center 7 ft of the 17 ft Gap we'll need to Bear approximately 17,000 lb spread evenly from the front of the cantilever to the back of the cantilever over 5 ft. I will put support beams across these cantilever arms to support the load evenly
View full post »

Similar threads

Spring and its shear, torsion, tensile stresses...
Replies
1
Views
2K
Shear Stress Distribution Along a Beam
Replies
3
Views
3K
Principal Stresses in a Shear Flow
Replies
1
Views
1K
How Do You Calculate Deflection and Shear Stress in a Tapered Shaft?
Replies
2
Views
3K
Shear stress damage due to thermal gradient
Replies
6
Views
2K
Determine how many bolts are needed to secure a block of steel
Replies
1
Views
2K
Shear flow in thin-walled members -- Hibbeler confusion
Replies
1
Views
3K
Self teaching basic average shear stress calculation
Replies
1
Views
2K
Load Shoulder Pressure Stress Calculations (Sketch Attached)
Replies
11
Views
4K
Engineering Calculating the safe load of a glued structure with given shear stress
Replies
5
Views
2K

Hot Threads

Recent Insights

Back
Top