MHD SIMULATION OF INTERACTIONS BETWEEN TWO NEIGHBORING INTERPLANETARY SHOCK WAVES-ANGULAR EFFECTS

The MHD 2(1/2)D, time-dependent model is used to investigate neighboringinterplanetary shock wave interactions in the equatorial plane, with different angular separations. For tow shocks with initial velocity v_s= 1000 km/s, the main results are: For the case of angular separation Δφ=24°, the two shock waves completely coalesced into a new shock within 1 AU; For the case of Δφ = 36°, the two shock waves coalesced into a new shock wave near 1AU; For the case of Δφ= 48°, the azimuthal collision of the two shocks occured, and a coalescence could partly be seen within 1 AU;For the case of Δφ = 72°, one would not almost see the collision of the two shock waves, that is their propagations are independent each other.For the two shocks with initial velocity v_s= 2000 km/s, main results are: For the case of Δφ ≤48°, the two shock waves completely coalesced into a new shock within 1 AU; For the case of 54°, the two shock waves coalesced into a new shock near 1 AU; For the case of Δφ = 72°, the two shock waves collided azimuthally, but could be identified from their distributions; For the case of Δφ = 120°, the two shock waves propagated independently.