Boundary Pressure Calculation for FSI #498
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svchb
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efaulhaber and
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efaulhaber
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## main #498 +/- ##
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- Coverage 69.37% 69.22% -0.16%
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Files 85 85
Lines 5124 5141 +17
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+ Hits 3555 3559 +4
- Misses 1569 1582 +13
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| pressure[particle] += (pressure_offset | ||
| + | ||
| particle_pressure(v_neighbor_system, neighbor_system, | ||
| neighbor) | ||
| + | ||
| dynamic_pressure(boundary_density_calculator, density_neighbor, | ||
| v, v_neighbor_system, particle, neighbor, | ||
| system, neighbor_system) | ||
| + | ||
| dot(resulting_acceleration, | ||
| density_neighbor * pos_diff)) * kernel_weight |
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| pressure[particle] += (pressure_offset | |
| + | |
| particle_pressure(v_neighbor_system, neighbor_system, | |
| neighbor) | |
| + | |
| dynamic_pressure(boundary_density_calculator, density_neighbor, | |
| v, v_neighbor_system, particle, neighbor, | |
| system, neighbor_system) | |
| + | |
| dot(resulting_acceleration, | |
| density_neighbor * pos_diff)) * kernel_weight | |
| # Bernoulli's principle | |
| stagnation_pressure = pressure_offset + | |
| particle_pressure(v_neighbor_system, neighbor_system, neighbor) + | |
| dynamic_pressure(boundary_density_calculator, density_neighbor, | |
| v, v_neighbor_system, particle, neighbor, | |
| system, neighbor_system) | |
| hydraulic_head = dot(resulting_acceleration, density_neighbor * pos_diff) | |
| pressure[particle] += (stagnation_pressure + hydraulic_head) * kernel_weight |
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But this is now used by both the adami and bernoulli pressure condition? Is this not just confusing?
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Hm it's the same principle. I was wondering if this might increase readability.
Co-authored-by: Erik Faulhaber <[email protected]>
…mi_pressure_changes
| #### 2. [`BernoulliPressureExtrapolation`](@ref) | ||
| Identical to [`AdamiPressureExtrapolation`](@ref), but it adds the dynamic pressure component of the Bernoulli equation: | ||
| ```math | ||
| \frac{1}{2} \, \rho_{\text{neighbor}} \left( \frac{ (\mathbf{v}_f - \mathbf{v}_{\text{neighbor}}) \cdot (\mathbf{x}_f - \mathbf{x}_{\text{neighbor}}) }{ \left\| \mathbf{x}_f - \mathbf{x}_{\text{neighbor}} \right\| } \right)^2 \times \text{factor} |
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- This now doesn't include the sign of the velocity difference. This seems wrong. The pressure should only increase when fluid and solid are moving towards each other, not away from each other, no?
- I don't find it very clear where this term is added exactly. Is it just added to the pressure of the Adami method? Is this even a pressure physically?
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-
what are you talking about? That is the equation:
-
It has the units of a pressure. Is this a physical pressure no.
| ```math | ||
| \frac{1}{2} \, \rho_{\text{neighbor}} \left( \frac{ (\mathbf{v}_f - \mathbf{v}_{\text{neighbor}}) \cdot (\mathbf{x}_f - \mathbf{x}_{\text{neighbor}}) }{ \left\| \mathbf{x}_f - \mathbf{x}_{\text{neighbor}} \right\| } \right)^2 \times \text{factor} | ||
| ``` | ||
| where ``v_f`` is the velocity of the fluid and ``v_\text{body}`` is the velocity of the body. |
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Please update this with the new symbols used in the equation.
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This is only unclear because this is only called for a moving body so relative_velocity is v_body-v_fluid_neighbor which is the relative velocity of the fluid to the body movement.
| normal_velocity = dot(relative_velocity, pos_diff) / distance | ||
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| return boundary_density_calculator.factor * density_neighbor * | ||
| dot(normal_velocity, normal_velocity) / 2 |
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This is not what you wrote in the docs, or am I missing something?
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see above this is identical to the equation
With the new BernoulliPressureExtrapolation on the right side
Depends on #599