# Sphere

The analytical solution for the potential flow around a sphere of radius $$R=1$$m and a uniform flow of $$|\mathbf{V}\_{ref}|=1$$ m/s is known. The perturbation (or doublet) potential is given by:

$$
\phi=|\mathbf{V}\_{ref}|cos(\theta)\frac{R^3}{2r^2}\text{,}
$$

where $$\phi$$ is the perturbation (or doublet) potential, $$R$$ is the radius of the sphere, $$r$$is the distance from the sphere centre to any point of interest on its surface, $$|\mathbf{V}\_{ref}|$$is the freestream velocity magnitude, and $$\theta$$is the angle between the $$x$$-axis and the projection of $$r$$on the $$x-z$$plane. An unstructured mesh of 532 elements is used. The image below shows the sphere pressure coefficient.

![](https://81269019-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-MV8htLPXN-_fWc_anY_%2F-Mh5GMP2mcFZe3xr5490%2F-Mh5LXKHzUdRlOA43q-D%2Fsphere_cp.png?alt=media\&token=a5137dc8-d339-41e9-966b-030fdb645e27)

The images below compare the perturbation potential, the total potential, and the pressure coefficient with the analytical solution.

<img src="https://81269019-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-MV8htLPXN-_fWc_anY_%2Fuploads%2FA5asdC0ElxzBrS3BpYWJ%2Fsphere_streamwise_mu.png?alt=media&#x26;token=b2712c79-a609-4fae-beca-9ce1dcffc593" alt="" data-size="original"> <img src="https://81269019-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-MV8htLPXN-_fWc_anY_%2Fuploads%2FvjgTUByPSoU7cZa73u08%2Fsphere_streamwise_phi.png?alt=media&#x26;token=393ad521-987b-4e6c-9be0-4eaea2c60dfa" alt="" data-size="original"> <img src="https://81269019-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-MV8htLPXN-_fWc_anY_%2Fuploads%2FDWS1VvDP3CxZgorgzCCI%2Fsphere_streamwise_cp.png?alt=media&#x26;token=da86de37-8a84-4401-b2e0-2e6e18d9196c" alt="" data-size="original">&#x20;

Good agreement between the simulation and the analytical solution is observed.

## Files

{% file src="<https://81269019-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-MV8htLPXN-_fWc_anY_%2F-MgbDrn8BW-2PFvQv56e%2F-MgbFgz2niNK6rIJuiBs%2Fsphere.zip?alt=media&token=f7e6f844-7cb8-47de-b0c8-016cb0ce27f6>" %}

## References


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