AirIntake

Air intake example to create a stable air flow field

This example shows how to set up an air intake simulation to get a stable and stationary air flow field. Furthermore it focuses on the EULERIMPL solver to save computation time for such test cases. The setup consists of a simple double walled tube within an air box: Here should be a picture

At the bottom of the tube the air is sucked in with a user given velocity. To check the results, the dynamic pressure is compared to the Bernoulli pressure based on the maximum velocity:

INTEGRATION($PDYN_MIN$) = (%MINIMUM_INT%, [Y%ind_p_corr%], $air$, %INTEGRATION_Header%, "p_dyn min") INTEGRATION($P_Bernoulli$) = (%PUBLICVALUE%, [-0.5*1.0*(integ($VEL_MAX$))^2], %INTEGRATION_Header%, "p_Bernoulli") INTEGRATION($DIFF_P_DYN_P_Bernoulli$) = (%PUBLICVALUE%, [abs(integ($PDYN_MIN$) - integ($P_Bernoulli$))], %INTEGRATION_Header%, "difference p_dyn - p_Bernoulli")

Recommended Settings

The best results can be achieved with the following settings:

Use constant density (purely incompressible).
damping_p_corr(1) = 0.0, so that the dynamic pressure is not considered for the initial guess in the next time level.
No use of boundary conditions for the dynamic pressure, e.g. BCON($xxx$,%ind_p_corr%) resp. BCON($xxx$,%ind_p_dyn%).
Static/Bernoulli pressure condition at box surface dependent on flow direction (see input file):

BC_p($air_out$) = (%BND_DIRICH%, equn{$StaticPressureAtOutflow$})

Results of Stationary Air Flow Field

Dynamic Pressure at t = 5: Here should be a picture

Velocity at t = 5: Here should be a picture