iter

h

$\Vert \nabla \left(u-u_h\right)\Vert$

$\Vert u-u_h\Vert$

$\Vert {\nabla }_{\tau }\left(u-Q_{\tau }{u}_h\right)\Vert$

$\Vert u-Q_{\tau }{u}_h\Vert$

1

2⁻³

0.3537e−0

0.2256e−1

0.2900e−0

0.2165e−1

2

3⁻³

0.1069e−0

0.2138e−2

0.5074e−1

0.2042e−2

3

4⁻³

0.4480e−1

0.3828e−3

0.1585e−1

0.3654e−3

4

5⁻³

0.2294e−1

0.1004e−3

0.6526e−2

0.9585e−4

5

6⁻³

0.1327e−1

0.3365e−4

0.3165e−2

0.3210e−4

$O\left(h^r\right)$

0.9962

1.9762

1.3686

1.9779