Simulation time parameters for IC engine

amin_u50 · September 22, 2017, 12:06

Hi,

I'm simulating dual-fuel engine and the engine speed is 900 rpm.

I defined initial time step, Min time step, and max time step as 1e-5, 1e-8,1e-4 sec, respectively. So, Why these are not based on the crank angle? If I even put these numbers, around spray injection timing and combustion phasing, CONVERGE calculate each 0.03 crank angle which is very low and time-consuming. If I increase it I face some errors. So, what do you recommend for the time step? Mostly it should be around 0.1 or 0.25 for the spray and combustion phasing.

tmburton · September 22, 2017, 12:17

Amin,

Time steps are calculated based on accuracy and stability requirements as prescribed by the various CFL values. We provide an Engine_sector_Diesel_DualFuel example case in Studio that will help you choose appropriate values.

Best regards,

Tristan

September 22, 2017, 12:06	Simulation time parameters for IC engine	#1
amin_u50 Senior Member amin u3fi Join Date: Feb 2013 Posts: 137 Rep Power: 13	Hi, I'm simulating dual-fuel engine and the engine speed is 900 rpm. I defined initial time step, Min time step, and max time step as 1e-5, 1e-8,1e-4 sec, respectively. So, Why these are not based on the crank angle? If I even put these numbers, around spray injection timing and combustion phasing, CONVERGE calculate each 0.03 crank angle which is very low and time-consuming. If I increase it I face some errors. So, what do you recommend for the time step? Mostly it should be around 0.1 or 0.25 for the spray and combustion phasing.

September 22, 2017, 12:17		#2
tmburton Member Tristan Burton Join Date: Sep 2017 Posts: 92 Rep Power: 8	Amin, Time steps are calculated based on accuracy and stability requirements as prescribed by the various CFL values. We provide an Engine_sector_Diesel_DualFuel example case in Studio that will help you choose appropriate values. Best regards, Tristan __________________ Tristan Burton Senior Principal Engineer CONVERGECFD

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