,How do I make the velocity of my sprite move in the same direction of its rotation?

I’m experimenting with Unity Remote 5, and I set up a simple scene with a wave and 2 buttons. The wave is constantly moving up. When I press the button on the left my sprite slightly rotates towards that direction, same with the right button. When a button is pressed, I want to change the velocity of my sprite to align with its current rotation

This is my script:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;

public class PlayerMove : MonoBehaviour
    public Rigidbody2D rb;
    public float movespeed;
    private float direction;
    public GameObject player;

    public Button leftBtn, rightBtn;
    int TappedLeft = 0;
    int TappedRight= 0;

    bool Right;
    bool Left;

    void Start()
        rb = GetComponent<Rigidbody2D>();

    // Update is called once per frame
    void Update()
        direction = Input.GetAxisRaw("Horizontal");
        rb.velocity = new Vector2(0f, movespeed);


    public void TiltLeft()

        if (TappedLeft < 1)
            player.transform.rotation = Quaternion.Euler(0f, 0f, 45f);
            TappedLeft += 1;
        TappedLeft -= 1;


    public void TiltRight()
        if (TappedRight < 1)
            player.transform.rotation = Quaternion.Euler(0f, 0f, -45f);
            TappedRight += 1;
        TappedRight -= 1;

Transform.forward is the forward vector of local relative rotation of the object