Simulation method, simulation method by MBD program, numerical analysis apparatus, numerical analysis system for MBD, numerical analysis program, and MBD program

A numerical analysis apparatus that simulates a cabin of a vehicle to numerically analyze a physical quantity, which includes airflow temperature in the cabin of the vehicle, in a physical phenomenon, the numerical analysis apparatus comprising:

• a communication device configured to exchange data with an external device;
• processing circuitry configured to
• obtain three-dimensional shape data of an analysis domain of the cabin of the vehicle from the external device via the communication device,
• divide the analysis domain into a plurality of divided domains, and
• generate a requested number of aggregated domains by aggregating the divided domains;
• and
• a storage configured to store
• a discretized governing equation with respect to the divided domains that uses only quantities that do not require coordinates of vertices of the divided domains and connectivity information on the vertices, and is derived by a weighted residual method, and
• a discretized governing equation with respect to the aggregated domains that uses only quantities that do not require coordinates of vertices of the aggregated domains and connectivity information on the vertices, and is derived by a weighted residual method,
• wherein the processing circuitry is configured to
• generate a calculation data model with respect to the divided domains based on the discretized governing equation with respect to the divided domains stored in the storage, the calculation data model including a volume of each divided domain and a divided-domain characteristic quantity representing a characteristic quantity of said each divided domain with respect to each adjacent divided domain as the quantities that do not require the coordinates of the vertices of the divided domains and the connectivity information on the vertices,
• generate a calculation data model with respect to the aggregated domains based on the discretized governing equation with respect to the aggregated domains stored in the storage, the calculation data model including a volume of each aggregated domain and an aggregated-domain characteristic quantity representing a characteristic quantity of said each aggregated domain with respect to each adjacent aggregated domain as the quantities that do not require the coordinates of the vertices of the aggregated domains and the connectivity information on the vertices,
• calculate, based on a physical property in the analysis domain and the calculation data model with respect to the aggregated domains, conductance representing a characteristic with respect to transfer of the physical quantity, which includes the airflow temperature in the cabin of the vehicle, between the aggregated domains and to the outside of the analysis domain, and capacitance representing a characteristic with respect to accumulation of the physical quantity, which includes the airflow temperature in the cabin of the vehicle, for each aggregated domain, and
• store the conductance and the capacitance in the storage, to enable an unsteady calculation of the physical quantity, which includes the airflow temperature in the cabin of the vehicle, in another analysis domain including the analysis domain.

A non-transitory computer-readable storage medium including a numerical analysis program, wherein the numerical analysis program, when executed by a computer, causes the computer to perform a method of simulating a cabin of a vehicle, the method comprising:

• obtaining, from an external device, three-dimensional shape data of an analysis domain of the cabin of the vehicle in which a physical quantity, which includes airflow temperature in the cabin of the vehicle, in a physical phenomenon is to be analyzed;
• dividing the analysis domain into a plurality of divided domains;
• generating a calculation data model with respect to the divided domains based on a discretized governing equation with respect to the divided domains that uses only quantities that do not require coordinates of vertices of the divided domains and connectivity information on the vertices, wherein the discretized governing equation is derived by a weighted residual method, and the calculation data model includes a volume of each divided domain and a divided-domain characteristic quantity representing a characteristic quantity of said each divided domain with respect to each adjacent divided domain as the quantities that do not require the coordinates of the vertices of the divided domains and the connectivity information on the vertices;
• generating a requested number of aggregated domains by aggregating the divided domains;
• generating a calculation data model with respect to the aggregated domains based on a discretized governing equation with respect to the aggregated domains that uses only quantities that do not require coordinates of vertices of the aggregated domains and connectivity information on the vertices, wherein the discretized governing equation is derived by a weighted residual method, and the calculation data model includes a volume of each aggregated domain and an aggregated-domain characteristic quantity representing a characteristic quantity of said each aggregated domain with respect to each adjacent aggregated domain as the quantities that do not require the coordinates of the vertices of the aggregated domains and the connectivity information on the vertices;
• calculating, based on a physical property in the analysis domain and the calculation data model with respect to the aggregated domains, conductance representing a characteristic with respect to transfer of the physical quantity, which includes the airflow temperature in the cabin of the vehicle, between the aggregated domains and to the outside of the analysis domain, and capacitance representing a characteristic with respect to accumulation of the physical quantity, which includes the airflow temperature in the cabin of the vehicle, for each aggregated domain;
• and
• storing the conductance and the capacitance in a memory of the computer, to enable an unsteady calculation of the physical quantity, which includes the airflow temperature in the cabin of the vehicle, in another analysis domain including the analysis domain.