Recent content by thepopasmurf

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    Is this a valid way to calculate capillary force / pressure?

    Thank you for your responses and help,
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    Is this a valid way to calculate capillary force / pressure?

    Hmm, maybe I should demonstrate what I mean for clarification: Cylindrical tube: fc = γ cos θ dS/dx, Surface area in cylinder, S = 2πrx Cross-sectional area, A = πr2 So Pc = fc/A = 2πrγ cosθ / πr2 Pc = 2γ cosθ / r Yeah! Correct answer Rectangular tube, w*h*x (x is direction of fluid...
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    Is this a valid way to calculate capillary force / pressure?

    When figuring out the capillary pressure on a liquid in a tube of a certain cross-section, the typical approach is to consider the Young-Laplace pressure and the curvature etc. I was looking through some of my old notes and I had an equation for the capillary force: fc = γ cosθ dS/dx where γ...
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    Melted cheese-like flow -- What is it called and its cause?

    @Asymptotic, this effect seems close to what I am looking for. The wikipedia entry doesn't give much to build on, I guess 'stretching' and 'fingering' are the best things to look at.
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    Melted cheese-like flow -- What is it called and its cause?

    There are some plastics I am using that when melted, pull apart in a stringy way. My best comparison is like melted cheese in a sandwich. I want to know more about this, but other than looking up 'polymer rheology', I'm not sure what I should call this type of flow. I want to know what causes...
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    Odds of Collision between Incident Object and Target Objects

    Homework Statement The problem is what are the odds of an incident object of radius r1 colliding with any of a collection of target objects of radius r2, where the r2 objects have a number density N / m^3 = n and the incident object travels a distance L. Incident object is moving much faster...
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    Particle-photon interaction to create new particle

    Ok, so here's my reworking of the problem: In lab frame four-momentum is: p_p + p_{\gamma} The square of this is invariant (p_p + p_{\gamma})\cdot(p_p + p_{\gamma}) = \frac{E_p^2}{c^2} - p_p^2 + \frac{E_{\gamma}^2}{c^2} - p_{\gamma}^2 + \frac{2E_pE_{\gamma}}{c^2} - 2p_p\cdot...
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    Particle-photon interaction to create new particle

    Homework Statement A particle with known rest mass energy, m_{p} c^{2} pass through a cloud of monoenergetic photons with energy E_{\gamma}. The particle collides with a photon and a particle A, with mass m_A is created. Show that the minimum energy of the particle required for the interaction...
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    Numerical Integration over 3D mesh

    I'm sorry that this is frustrating for you, but I'm not yet convinced that the area of the triangles is exactly what I want. I'll try to explain my approach in more detail. I have a mesh of an object made up of triangular faces. I'm trying to get the spherical harmonics components of the mesh...
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    Numerical Integration over 3D mesh

    So should I change my integrand from \int Y R d\Omega to \int \frac{Y}{R} dA to keep the units correct?
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    Numerical Integration over 3D mesh

    I think it's fine that it's on a unit sphere because the distance part is accounted for in the integrand. And I'm not sure why I would have to add an extra R just because the function is the radius rather than any other function. Anyway, I think we're getting distracted by this point. I'm...
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    Numerical Integration over 3D mesh

    As far as I'm aware that is the correct element to integrate over. http://shtools.ipgp.fr/www/conventions.html Look for f_lm around a quarter way down the page http://en.wikipedia.org/wiki/Spherical_harmonics#Spherical_harmonics_expansion See the integrals in this section.
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    Numerical Integration over 3D mesh

    The purpose of the integral is not to find the area, but to find the harmonic coefficients of R.
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