Hi Brad,
Thank you for your help. Sorry that I don't know how to upload pictures into the forum to show the problem.
I inserted a Disc object in the medium using "makeDisc" function in the 2D example_tvsp_homogeneous_medium_monopole.m . I define the medium speed=1500m/s and the medium density=1000kg/m^3, and the Disc speed=6000m/s and the medium density=1500kg/m^3.
source.p = source_mag*sin(2*pi*source_freq*kgrid.t_array); % sinusoidal wave
sensor_data = kspaceFirstOrder2D(kgrid, medium, source, sensor, input_args{:});
sensor_data_record = sensor_data.p; % recorded data
The problem is that I even use source_mag = 1e-12 for the source magnitude (extremely small magnitude), the resulting sensor_data.p data range from 10^-29 (1st data) to 10^9 (last data), the data is extremely large (i.e. 10^9). The wavefield display gradually shows the Disc shape in black, and then entire wavefield display turns to be black (I guess it may be because the sensor_data.p is too large).
However, when the Disc speed is less than 6000m/s (e.g. 5000, 3000), everything looks normal. But when the Disc speed is greater than 6000m/s, this problem occurs.
I was wondering if you know what the problem is for this kind of high-speed objects in the simulations?
Many thanks,
John