[Aashi171185]

Hello sir i am doing sloshing analysis in closed circular tank and i am using hexa meshing with inflation of total thickness of 5mm with 5 layers sir my problem is when i start the analysis in cfx solver it shows expansion factor of 229! in mesh quality statistics i want to know is it ok with high expansion factor for my case? i mean is it producing any convergence issues? my aspect ratio and orthog angle is in acceptable range

[ghorrocks]

I should write an FAQ on this:

The mesh quality thresholds are really guidelines. The real sensitivity to mesh quality depends on the simulation. Some simulations can handle much worse quality meshes, some require far better quality meshes than the thresholds for reasonable results.

The best way to be sure is to generate some meshes of varying quality and see what the sensitivity is in your case.

In your case I would think a free surface simulation will not work well if the aspect ratio 229 elements are near the free surface. Free surface models need much better quality meshes than the threshold to run accurately. If the poor elements are away from the free surface then you might be OK.

[Aashi171185]

Thank you sir for your kind guidance and help sir my mesh quality is shown below

Mesh Statistics |
+--------------------------------------------------------------------+
| Domain Name | Orthog. Angle | Exp. Factor | Aspect Ratio |
+----------------------+---------------+--------------+--------------+
| | Minimum [deg] | Maximum | Maximum |
+----------------------+---------------+--------------+--------------+
| Default Domain | 39.4 ok | 226 ! | 260 OK |
+----------------------+---------------+--------------+--------------+
| | %! %ok %OK | %! %ok %OK | %! %ok %OK |
+----------------------+---------------+--------------+--------------+
| Default Domain | 0 2 98 | 6 0 94 | 0 0 100 |
+----------------------+---------------+--------------+--------------+
with this my monitoring pressure comes out to be 43696[pa] and with improvement in mesh quality like orthog Angle became=42.7 ok
Expansion factor became= 6 ok and aspect ratio became 6 OK my pressure became 43618[pa]
Sir i my case inflation effects the mesh quality as i induce total thickness of 5mm with 5 layers it reduces the mesh quality else with the first layer thickness of 30 mm increases the mesh quality to acceptable level as mentioned above sir your guidance is highly appreciated and required guide me to go on with poor expansion factor or need to improve it

[ghorrocks]

Doesn't your results show that your original mesh had pressure of 43696Pa and mesh quality improvements changed that to 43618Pa? That is a change of less than 1%. Most people don't need that sort of accuracy. If this is the case then it suggests the mesh quality improvements you did caused no significant change in results, and are therefore not required.

To really understand you mesh quality requirement you should do a simple model, like a cube, partially filled with fluid and do your sloshing simulation in that. This will allow you to easily test the perfect mesh (aspect ratio 1 hexs), tets, aspect ratios and other mesh quality parameters. It should also run pretty quickly. This simple model will allow you to understand the effect of mesh quality for you.