From c900b7ca16bdca8c3c272a4cba7b45c330e82f68 Mon Sep 17 00:00:00 2001 From: Justin Angus Date: Mon, 19 Aug 2024 10:15:50 -0700 Subject: [PATCH] updating comments. --- .../Coulomb/UpdateMomentumPerezElastic.H | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/Source/Particles/Collision/BinaryCollision/Coulomb/UpdateMomentumPerezElastic.H b/Source/Particles/Collision/BinaryCollision/Coulomb/UpdateMomentumPerezElastic.H index 37ccc1d7630..37ef212e4a9 100644 --- a/Source/Particles/Collision/BinaryCollision/Coulomb/UpdateMomentumPerezElastic.H +++ b/Source/Particles/Collision/BinaryCollision/Coulomb/UpdateMomentumPerezElastic.H @@ -66,7 +66,7 @@ void UpdateMomentumPerezElastic ( T_PR const p2y = u2y * m2; T_PR const p2z = u2z * m2; - // Compute center-of-mass (COM) velocity and gamma + // Compute center-of-momentum (COM) velocity and gamma T_PR const mass_g = m1 * g1 + m2 * g2; T_PR const vcx = (p1x+p2x) / mass_g; T_PR const vcy = (p1y+p2y) / mass_g; @@ -105,13 +105,15 @@ void UpdateMomentumPerezElastic ( T_PR const g1s = ( T_PR(1.0) - vcDv1*inv_c2 )*gc*g1; T_PR const g2s = ( T_PR(1.0) - vcDv2*inv_c2 )*gc*g2; - // Compute variant relative velocity in center-of-mass frame + // Compute relative velocity in center-of-momentum frame + // (not a Lorentz invariant quantity) T_PR const muRst = g1s*m1*g2s*m2/(g1s*m1 + g2s*m2); - T_PR const vrelst = p1sm/muRst; + T_PR const vrelst = p1sm/muRst; // |v1s - v2s| - // Compute invariant relative velocity (frame independent) + // Compute invariant relative velocity in center-of-momentum frame + // (Lorentz invariant quantity) T_PR const denom = T_PR(1.0) + p1sm*p1sm/(m1*g1s*m2*g2s)*inv_c2; // (1.0 - v1s*v2s/c^2) - T_PR const vrelst_invar = vrelst/denom; + T_PR const vrelst_invar = vrelst/denom; // |v1s - v2s|/(1.0 - v1s*v2s/c^2) // Compute s12 T_PR s12 = 0;