Access the particle system velocity inheritance module.
using UnityEngine; using System.Collections;
public class ExampleClass : MonoBehaviour { void Start() { ParticleSystem ps = GetComponent<ParticleSystem>(); var iv = ps.inheritVelocity; iv.enabled = true;
AnimationCurve curve = new AnimationCurve(); curve.AddKey( 0.0f, 1.0f ); curve.AddKey( 1.0f, 0.0f ); iv.curve = new ParticleSystem.MinMaxCurve(1.0f, curve); } }