Table 4 Errors and computational orders of central difference scheme for V

\(\frac{1}{10}\)

\(\frac{1}{{10}^{2}}\)

8.573e−02

–

4.286e−02

–

\(\frac{1}{20}\)

\(\frac{1}{{20}^{2}}\)

1.447e−02

2.57

7.237e−03

2.57

\(\frac{1}{30}\)

\(\frac{1}{{30}^{2}}\)

6.001e−03

2.17

3.006e−03

2.17

\(\frac{1}{40}\)

\(\frac{1}{{40}^{2}} \)

3.304e−03

2.08

1.652e−03

2.08

\(\frac{1}{50}\)

\(\frac{1}{{50}^{2}}\)

2.092e−03

2.05

1.046e−03

2.05

\(\frac{1}{60}\)

\(\frac{1}{{60}^{2}}\)

1.445e−03

2.03

7.225e−04

2.03