Recent content by LmdL

Never mind. I need to review my understading of optical tweezers. Thank you for your help!

Thank you for your reply. I got your point. I have an additional question: let's suppose I place a particle on the z axis (in the waves overlapping area) and restrict it to move along z axis, for example by adding two transparent parallel to z axis plates, one slightly above it and one slightly...

Hello, I'm considering the "beats" phenomena. I have two plane waves in some medium with a refractive index n(ω), one propagates in a z direction and second in a direction making an angle θ with z axis. Waves have frequencies ω1, ω2 (not necessarily equal) and k-vectors k1, k2 (not necessarily...

Hello again, If I take a friction factor of ##f_D\approx 64/Re = 64/1.5=42.7## I indeed get, as you correctly pointed out, a negligible pressure drop: $$\Delta P = f_D \frac{L}{D}\frac{\rho_1 u_1^2}{2} = 42.7 \frac{1 \text{m}}{0.01 \text{m}}\frac{0.1 \frac{\text{kg}}{\text{m}^3} \left( 0.032...

As I understand, the mean velocity in pipe you got using the Bernoulli equation. Regarding the Moody chart, if I calculate the Reynolds number for my case (Dynamic viscosity of Ar: ## \mu = 2.2 \cdot 10^{-5} \; \text{Pa} \cdot \text{s} ##): $$Re = \frac{\rho V_{avg}D}{\mu} = \frac{0.1...

Dear jrmichler, I set ##P_1 = 50 \; \text{torr}## and ##P_3 = 0 \; \text{torr}## (outside of the pipe, after the orifice). Pressure ##P_2## (end of the pipe, just before the orifice) is my variable which I set as an array running from ##0## to ##50 \; \text{torr}##. Calculation of the flow...

Dear jrmichler, First of all, thank you very much for a quick and detailed response! In addition, I want to record here my steps to be sure I'm not doing nonsense calculations at any step. I went over the Moody chart that describes the friction factor as a function of the Reynolds number for...

Hello, The question will probably be related to mechanical engineering / chemical engineering / aeronautics. I come from the field of optics and have no background at all on fluid dynamics. I'm trying to calculate the dependence of pressure on distance, i.e. P(x) in a gas flow problem: I...

I'm in doubt if there is a simpler expression involving q,m,π and probably n (integer). Without trigonometric functions.

In general, for my purpose, both are continuous.

I have a trigonometric equation 2\sin \left ( \frac{q\pi }{m} \right )-\sin \left ( \frac{q\pi }{2} \right )=0 and want to know what values m as a function of q could take to satisfy the equation. Both terms zero is the obvious solution: q=2n; m=2; n is an integer. But there are more solutions...

Thanks guys! I already found the answer myself, which is: in the above case, Fourier transform is real (without imaginary part), so if I want to represent the amplitude on the screen I will write: Y=Aasinc\left ( \pi ka \right )=Re^{i \phi} since the transform is real, Φ can be either zero or...

Hello, I'm trying to understand how can I compute a phase graph from diffraction. I will follow here Fourier transform formalism of finding the light distribution on screen after diffraction. I'm considering a 1D problem. Suppose I have a single slit of width a. This slit can be mathematically...

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Hello, I'm trying to calculate a recurrence relation of the phases of 3 telescopes in a closure phase. Usually in a stellar interferometer we have 3 telescopes, located in a triangle, measuring intensity of light in 3 points on a far field plane. I found an article, describing how the phase is...