Most Popular
1500 questions
5
votes
1 answer
Wall functions and separation in turbine blade simulation
I am simulating a turbine and I have some question about standard wall function in FLUENT.
Standard wall function requires $y^+$ value between 30 to 60 on the blade. but the following quote states:
When using wall function models, the $y^+$ value…
user19061
- 899
- 10
- 14
5
votes
2 answers
Why do the poles and zeroes of a transfer function cause a slope change in frequency response?
Why is it that as the frequency approaches a pole or zero of a system, the slope of the magnitude of the transfer function changes by 20dB/decade?
Whenever I see this stated when reading about transfer functions, it's never explained. What causes…
new_response
- 51
- 2
5
votes
0 answers
Are Green strain calculations apt for volumetric strains?
I am trying to calculate large volumetric strains but I am somewhat confused whether Green strain is the right thing to be using or whether I should use good old-fashioned engineering strain.
The work I am doing is looking at strain of a deformable…
Munki Fisht
- 51
- 1
5
votes
2 answers
How hot does a rocket nose cone get during launch?
More specifically, I'd like to know if unmanned rockets need to be specially designed to withstand the heat generated from air friction and shock waves during launch. I found the diagram below on the NASA website which shows some fairly high…
Carlton
- 3,054
- 2
- 12
- 27
5
votes
2 answers
Why choose approximation over interpolation to implement digital lofting?
Before widespread use of digital computers lofting was done using a thin flexible strip, called spline, held in place by a series of weights. This technique is a type of interpolation (curve exactly passes over sample points) using a physical analog…
user3368561
- 749
- 5
- 11
5
votes
2 answers
How to calculate deflection of a simple beam with a load in the center?
Given this type of arrangement:
- image by Hermanoere
Where the beam is of rectangular cross-section.
I am specifically thinking of a wooden beam where I can look up some material characteristics (e.g. modulus of elasticity) from places such as…
RedGrittyBrick
- 151
- 1
- 1
- 6
5
votes
1 answer
How could we possibly harness the energy from the Earth's negative charge?
I've been reading the Feynman lectures, and in this lecture about lightning, he describes how the Earth is negatively charged, and how there is thus an electric field of about $100\ \tfrac{\text{V}}{\text{m}}$ near the surface of the earth.
To me,…
QCD_IS_GOOD
- 167
- 2
5
votes
3 answers
Center of Pressure Line from Barefoot Scan (EMED)
I have raw data obtained from EMED barefoot scan containing a matrix of pressure sensors over about 70 frames. This totals 70 matrices that record a snapshot of the pressure over the duration of a person's natural walk over the pressure plate.
I…
blaklaybul
- 151
- 4
5
votes
2 answers
What could be the downsides of leaving twist-off bolt splines in the interior of exterior columns?
I have a project where the contractor is using ASTM F1852 Tension Control (twist-off) bolts. The project is outdoors and uses weathering steel and weathering fasteners. The main members are hollow steel sections that are utilizing bolted splices.…
hazzey
- 10,711
- 10
- 44
- 94
5
votes
1 answer
Determine the range of values for a PI controller
This is a basic control theory question, since Control Theory is a part of applied mathematics but also of engineering I was unsure whether to ask this here.
The question says:
Given the transfer function of a system is $G(s)=1/(s^2+3s+2)$,…
HCalderon
- 53
- 4
5
votes
2 answers
ANSYS Workbench/Mechanical: Automatically export chart?
I'm running a simple tensile test simulation for a single element. Under Results I made a Chart object with Stress vs Strain, which can be manually exported to a csv file by right clicking on the table. The trouble arises from the parametrization.…
rysciguy
- 53
- 1
- 4
5
votes
1 answer
What is a non-equilibrium boundary layer?
I studied a manual of Ansys CFX about turbulence models and I came across the term "non equilibrium boundary layer". What does this term mean?
user19061
- 899
- 10
- 14
5
votes
1 answer
What is the difference between being UL recognized and being UL listed?
A product can be UL recognized or UL listed. I understand that there is some difference between these two things, but I have never had a full and clear explanation of the difference. What is, in fact, the difference?
Stephen Collings
- 1,675
- 1
- 18
- 27
5
votes
1 answer
How do I interpret the curing pressure of a composite from this data sheet?
A question asked about the necessary curing pressures for a composite resin in the autoclave. Looking through the corresponding datasheet (HexPly F155), I'm confused:
Cure Procedure
Apply vacuum of 22 inches (74 kPa) Hg minimum.
Apply 85 + 15 – 0…
BeyondLego
- 950
- 6
- 11
5
votes
1 answer
What's the smallest pin-like hole I can machine into a piece of tungsten using a metal lathe and common carbide tools?
I am going to machine something out of a small 40mm long x 8mm diam tungsten rod. The majority will be hollowed out using a larger bit, but at the very tip, I need a small hole, the smaller the better between .05mm and .6mm. I understand an L/D…
Daniel Donnelly
- 423
- 3
- 12